Add CI workflow to lint TypeScript and JavaScript code

On every push and pull request that affects relevant files, and periodically, run eslint on the repository's TypeScript
and JavaScript files.

eslint is configured via the .eslintrc.yml file:
https://eslint.org/docs/user-guide/configuring/configuration-files

Author: per1234

.eslintignore

@@ -0,0 +1,3 @@
+dist
+lib
+node_modules

.eslintrc.yml

@@ -0,0 +1,29 @@
+# See: https://github.com/typescript-eslint/typescript-eslint/blob/master/docs/getting-started/linting/README.md#configuration
+
+extends:
+  - airbnb-typescript/base
+  - prettier
+plugins:
+  - "@typescript-eslint"
+parser: "@typescript-eslint/parser"
+parserOptions:
+  project:
+    - ./tsconfig.eslint.json
+rules:
+  max-len:
+    - error
+    - code: 180
+  "@typescript-eslint/comma-dangle": "off"
+  no-console: "off"
+  padded-blocks: "off"
+  "@typescript-eslint/indent":
+    - error
+    - 2
+    - SwitchCase: 1
+  spaced-comment: warn
+  arrow-parens: "off"
+  consistent-return: "off"
+  no-useless-escape: "off"
+  no-underscore-dangle: "off"
+  import/prefer-default-export: "off"
+  "@typescript-eslint/type-annotation-spacing": error

.github/workflows/check-typescript-task.yml

@@ -0,0 +1,54 @@
+name: Check TypeScript
+
+# See: https://docs.github.com/en/actions/reference/events-that-trigger-workflows
+on:
+  push:
+    paths:
+      - ".github/workflows/check-typescript-task.yml"
+      - ".eslintignore"
+      - "**/.eslintrc*"
+      - "package.json"
+      - "package-lock.json"
+      - "Taskfile.yml"
+      - "tsconfig.eslint.json"
+      - "tsconfig.json"
+      - "**.js"
+      - "**.jsx"
+      - "**.ts"
+      - "**.tsx"
+  pull_request:
+    paths:
+      - ".github/workflows/check-typescript-task.yml"
+      - ".eslintignore"
+      - "**/.eslintrc*"
+      - "package.json"
+      - "package-lock.json"
+      - "Taskfile.yml"
+      - "tsconfig.eslint.json"
+      - "tsconfig.json"
+      - "**.js"
+      - "**.jsx"
+      - "**.ts"
+      - "**.tsx"
+  schedule:
+    # Run every Tuesday at 8 AM UTC to catch breakage caused by changes to tools.
+    - cron: "0 8 * * TUE"
+  workflow_dispatch:
+  repository_dispatch:
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      - name: Install Taskfile
+        uses: arduino/actions/setup-taskfile@master
+        with:
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
+          version: 3.x
+
+      - name: Lint
+        run: task ts:lint

README.md

@@ -1,5 +1,6 @@
 # `arduino/setup-taskfile`
 
+[![Check TypeScript status](https://github.com/arduino/setup-taskfile/actions/workflows/check-typescript-task.yml/badge.svg)](https://github.com/arduino/setup-taskfile/actions/workflows/check-typescript-task.yml)
 [![Integration Tests status](https://github.com/arduino/setup-taskfile/actions/workflows/test-integration.yml/badge.svg)](https://github.com/arduino/setup-taskfile/actions/workflows/test-integration.yml)
 [![Check Action Metadata status](https://github.com/arduino/setup-taskfile/actions/workflows/check-action-metadata-task.yml/badge.svg)](https://github.com/arduino/setup-taskfile/actions/workflows/check-action-metadata-task.yml)
 [![Spell Check status](https://github.com/arduino/setup-taskfile/actions/workflows/spell-check.yml/badge.svg)](https://github.com/arduino/setup-taskfile/actions/workflows/spell-check.yml)

Taskfile.yml

@@ -9,6 +9,25 @@ tasks:
     deps:
       - task: action:validate
 
+  ts:install-deps:
+    desc: Install TypeScript development dependencies
+    cmds:
+      - npm install
+
+  ts:lint:
+    desc: Lint TypeScript code
+    deps:
+      - task: ts:install-deps
+    cmds:
+      - npx eslint --ext .js,.jsx,.ts,.tsx .
+
+  ts:fix-lint:
+    desc: Fix TypeScript code linting violations
+    deps:
+      - task: ts:install-deps
+    cmds:
+      - npx eslint --ext .js,.jsx,.ts,.tsx --fix .
+
   action:validate:
     desc: Validate GitHub Actions metadata against JSON schema
     cmds: