Implemented eventarc event publishing API (#1617)

Author: pavelgj

entrypoints.json

@@ -55,5 +55,9 @@
   "firebase-admin/remote-config": {
     "typings": "./lib/remote-config/index.d.ts",
     "dist": "./lib/remote-config/index.js"
+  },
+  "firebase-admin/eventarc": {
+    "typings": "./lib/eventarc/index.d.ts",
+    "dist": "./lib/eventarc/index.js"
   }
 }

etc/firebase-admin.eventarc.api.md

@@ -0,0 +1,51 @@
+## API Report File for "firebase-admin.eventarc"
+
+> Do not edit this file. It is a report generated by [API Extractor](https://api-extractor.com/).
+
+```ts
+
+/// <reference types="node" />
+
+import { Agent } from 'http';
+
+// @public
+export class Channel {
+    readonly allowedEventTypes?: string[];
+    get eventarc(): Eventarc;
+    get name(): string;
+    publish(events: CloudEvent | CloudEvent[]): Promise<void>;
+}
+
+// @public
+export interface ChannelOptions {
+    allowedEventTypes?: string[] | string | undefined;
+}
+
+// @public
+export interface CloudEvent {
+    [key: string]: any;
+    data?: object | string;
+    datacontenttype?: string;
+    id?: string;
+    source?: string;
+    specversion?: CloudEventVersion;
+    subject?: string;
+    time?: string;
+    type: string;
+}
+
+// @public
+export type CloudEventVersion = '1.0';
+
+// @public
+export class Eventarc {
+    // Warning: (ae-forgotten-export) The symbol "App" needs to be exported by the entry point index.d.ts
+    get app(): App;
+    channel(name: string, options?: ChannelOptions): Channel;
+    channel(options?: ChannelOptions): Channel;
+}
+
+// @public
+export function getEventarc(app?: App): Eventarc;
+
+```