feat(ui): add firebase_ui_auth and oauth providers

packages/firebase_ui_auth/.gitignore

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+# Miscellaneous
+*.class
+*.log
+*.pyc
+*.swp
+.DS_Store
+.atom/
+.buildlog/
+.history
+.svn/
+migrate_working_dir/
+
+# IntelliJ related
+*.iml
+*.ipr
+*.iws
+.idea/
+
+# The .vscode folder contains launch configuration and tasks you configure in
+# VS Code which you may wish to be included in version control, so this line
+# is commented out by default.
+#.vscode/
+
+# Flutter/Dart/Pub related
+# Libraries should not include pubspec.lock, per https://dart.dev/guides/libraries/private-files#pubspeclock.
+/pubspec.lock
+**/doc/api/
+.dart_tool/
+.packages
+build/

packages/firebase_ui_auth/.metadata

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+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: f1875d570e39de09040c8f79aa13cc56baab8db1
+  channel: stable
+
+project_type: package

packages/firebase_ui_auth/CHANGELOG.md

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+## 1.0.0-dev.0
+
+ - Bump "firebase_ui_auth" to `1.0.0-dev.0`.
+
+## 0.0.1
+
+* TODO: Describe initial release.

packages/firebase_ui_auth/LICENSE

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+Copyright 2017, the Chromium project authors. All rights reserved.
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+    * Neither the name of Google Inc. nor the names of its
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

packages/firebase_ui_auth/README.md

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+# Firebase UI Auth
+
+[![pub package](https://img.shields.io/pub/v/firebase_ui_auth.svg)](https://pub.dev/packages/firebase_ui_auth)
+
+Firebase UI Auth is a set of Flutter widgets and utilities designed to help you build and integrate your user interface with Firebase Authentication.
+
+> Please contribute to the [discussion](https://github.com/firebase/flutterfire/discussions/6978) with feedback.
+
+## Platoform support
+
+| Feature/platform   | Android | iOS | Web              | macOS            | Windows          | Linux            |
+| ------------------ | ------- | --- | ---------------- | ---------------- | ---------------- | ---------------- |
+| Email              | ✓       | ✓   | ✓                | ✓                | ✓ <sup>(1)</sup> | ✓ <sup>(1)</sup> |
+| Phone              | ✓       | ✓   | ✓                | ╳                | ╳                | ╳                |
+| Email link         | ✓       | ✓   | ╳                | ╳                | ╳                | ╳                |
+| Email verification | ✓       | ✓   | ✓ <sup>(2)</sup> | ✓ <sup>(2)</sup> | ✓ <sup>(1)</sup> | ✓ <sup>(1)</sup> |
+| Sign in with Apple | ╳       | ✓   | ╳                | ✓                | ╳                | ╳                |
+| Google Sign in     | ✓       | ✓   | ✓                | ✓                | ✓ <sup>(1)</sup> | ✓ <sup>(1)</sup> |
+| Twitter Login      | ✓       | ✓   | ✓                | ✓                | ✓ <sup>(1)</sup> | ✓ <sup>(1)</sup> |
+| Facebook Sign in   | ✓       | ✓   | ✓                | ✓                | ✓ <sup>(1)</sup> | ✓ <sup>(1)</sup> |
+
+1. Available with [flutterfire_desktop](https://github.com/invertase/flutterfire_desktop)
+2. No deep-linking into app, so email verification link opens a web page
+
+## Installation
+
+```sh
+flutter pub add firebase_ui_auth
+```
+
+## Getting Started
+
+Here's a quick example that shows how to build a `SignInScreen` and `ProfileScreen` in your app
+
+```dart
+import 'package:flutter/material.dart';
+import 'package:firebase_auth/firebase_auth.dart';
+import 'package:firebase_ui_auth/firebase_ui_auth.dart';
+
+class MyApp extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    const providers = [EmailAuthProvider()];
+
+    return MaterialApp(
+      initialRoute: FirebaseAuth.instance.currentUser == null ? '/sign-in' : '/profile',
+      routes: {
+        '/sign-in': (context) {
+          return SignInScreen(
+            providers: providers,
+            actions: [
+              AuthStateChangeAction<SignedIn>((context, state) {
+                Navigator.pushReplacementNamed(context, '/profile');
+              }),
+            ],
+          );
+        },
+        '/profile': (context) {
+          return ProfileScreen(
+            providers: providers,
+            actions: [
+              SignedOutAction((context) {
+                Navigator.pushReplacementNamed(context, '/sign-in');
+              }),
+            ],
+          );
+        },
+      },
+    );
+  }
+}
+```
+
+Learn more [here](https://github.com/firebase/flutterfire/packages/firebase_ui_auth/doc/README.md).
+
+## Roadmap / Features
+
+- For issues, please create a new [issue on the repository](https://github.com/firebase/flutterfire/issues).
+- For feature requests, & questions, please participate on the [discussion](https://github.com/firebase/flutterfire/discussions/6978) thread.
+- To contribute a change to this plugin, please review our [contribution guide](https://github.com/firebase/flutterfire/blob/master/CONTRIBUTING.md) and open a [pull request](https://github.com/firebase/flutterfire/pulls).

packages/firebase_ui_auth/analysis_options.yaml

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+include: package:flutter_lints/flutter.yaml
+
+# Additional information about this file can be found at
+# https://dart.dev/guides/language/analysis-options

packages/firebase_ui_auth/doc/README.md

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+# Firebase UI for authentication
+
+Firebase UI for authentication provides a simple and easy way to implement authentication in your Flutter app.
+The library provides fully featured UI screens to drop into new or existing applications, along with
+lower level abstractions for developers looking for tighter control.
+
+## Installation
+
+Activate FlutterFire CLI
+
+```sh
+dart pub global activate flutterfire_cli
+```
+
+Install dependencies
+
+```sh
+flutter pub add firebase_core
+flutter pub add firebase_auth
+# required for email link sign in and email verification
+flutter pub add firebase_dynamic_links
+flutter pub add firebase_ui_auth
+```
+
+## Configuration
+
+Configure firebase using cli:
+
+```sh
+flutterfire configure
+```
+
+Initialize firebase app:
+
+```dart
+void main() {
+  WidgetsFlutterBinding.ensureInitialized();
+
+  await Firebase.initializeApp(options: DefaultFirebaseOptions.currentPlatform);
+}
+```
+
+## macOS entitlements
+
+If you're building for macOS, make sure to add necessary entitlements. Learn more [from the official Flutter documentation](https://docs.flutter.dev/development/platform-integration/macos/building).
+
+## Next steps
+
+To understand what Firebase UI for authentication offers, the following documentation pages walk you through the various topics on
+how to use the package within your Flutter app.
+
+- Available auth providers:
+
+  - [EmaiAuthProvider](./providers/email.md) - allows registering and signing in using email and password.
+  - [EmailLinkAuthProvider](./providers/email-link.md) - allows registering and signing in using a link sent to email.
+  - [PhoneAuthProvider](./providers/phone.md) - allows registering and signing in using a phone number
+  - [UniversalEmailSignInProvider](./providers/universal-email-sign-in.md) - gets all connected auth providers for a given email.
+  - [OAuth](./providers/oauth.md)
+
+- [Localization](../../firebase_ui_localizations/README.md)
+- [Theming](./theming.md)
+- [Navigation](./navigation.md)

packages/firebase_ui_auth/doc/navigation.md

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+# Navigation
+
+Firebase UI uses Flutter navigation capabilities to navigate between pages.
+
+By default, it uses "Navigator 1." when a new screen needs to be shown as a result of user interaction (`Navigator.push(context, route)` is used).
+
+For applications using the standard navigation APIs, navigation will work out of the box and require no intervention. However, for applications using
+a custom routing package, you will need to override the default navigation actions to integrate with your routing strategy.
+
+## Custom routing
+
+For this example, the application will create [named routes](https://docs.flutter.dev/cookbook/navigation/named-routes). Within the UI logic, we can
+override the default actions (e.g. signing in or signing out) the UI performs to instead integrate with those named routes.
+
+First, we define the root route that checks for authentication state and renders a `SignInScreen` or `ProfileScreen`:
+
+```dart
+class MyApp extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    const providers = [EmailProvider()];
+
+    return MaterialApp(
+      initialRoute: FirebaseAuth.instance.currentUser == null ? '/sign-in' : '/profile',
+      routes: {
+        '/sign-in': (context) => SignInScreen(providers: providers),
+        '/profile': (context) => ProfileScreen(providers: providers),
+      },
+    );
+  }
+}
+```
+
+By default, when a user triggers a sign-in via the `SignInScreen`, no action default occurs. Since we are not subscribing to the authentication
+state (via the `authStateChanges` API), we need to manually force the navigator to push to a new screen (the `/profile` route).
+
+To do this, add a `AuthStateChangeAction` action to the `actions` property of the widget, for example for a successful sign in:
+
+```dart
+SignInScreen(
+  actions: [
+    AuthStateChangeAction<SignedIn>((context, _) {
+      Navigator.of(context).pushReplacementNamed('/profile');
+    }),
+  ],
+  // ...
+)
+```
+
+You could also react to the user signing out in a similar manner:
+
+```dart
+ProfileScreen(
+  actions: [
+    SignedOutAction((context, _) {
+      Navigator.of(context).pushReplacementNamed('/sign-in');
+    }),
+  ],
+  // ...
+)
+```
+
+Some UI widgets also come with internal actions which triggers navigation to a new screen. For example the `SignInScreen` widget allows users to
+reset their password by pressing the "Forgot Password" button, which internally navigates to a `ForgotPasswordScreen`. To override this action and
+navigate to a named route, provide the `actions` list with a `ForgotPasswordAction`:
+
+```dart
+class MyApp extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    const providers = [EmailProvider()];
+
+    return MaterialApp(
+      initialRoute: FirebaseAuth.instance.currentUser == null ? '/sign-in' : '/profile',
+      routes: {
+        '/sign-in': (context) {
+          return SignInScreen(
+            providers: providers,
+            actions: [
+              ForgotPasswordAction((context, email) {
+                Navigator.of(context).pushNamed(
+                  '/forgot-password',
+                  arguments: {'email': email},
+                );
+              }),
+            ],
+          );
+        },
+        '/profile': (context) => ProfileScreen(providers: providers),
+        '/forgot-password': (context) => MyCustomForgotPasswordScreen(),
+      },
+    );
+  }
+}
+```
+
+To learn more about the available actions, check out the [FirebaseUIActions API reference](https://pub.dev/documentation/firebase_ui_auth/latest/firebase_ui_auth/FirebaseUIActions-class.html).
+
+## Other topics
+
+## Other topics
+
+- [EmaiAuthProvider](./providers/email.md) - allows registering and signing using email and password.
+- [EmailLinkAuthProvider](./providers/email-link.md) - allows registering and signing using a link sent to email.
+- [PhoneAuthProvider](./providers/phone.md) - allows registering and signing using a phone number
+- [UniversalEmailSignInProvider](./providers/universal-email-sign-in.md) - gets all connected auth providers for a given email.
+- [OAuth](./providers/oauth.md)
+- [Localization](../../firebase_ui_localizations/README.md)
+- [Theming](./theming.md)