Introduce CLI Starter Kit, create-yorkie-app (#643)

This commit introduces CLI starter kit, enabling users to easily
scaffold Yorkie-based cooperative applications. The goal is to provide
a convenient way for users to kickstart their projects using Yorkie.

All source codes related to this pull request have been organized
within the tools/create-yorkie-app directory.

.github/workflows/create-yorkie-app-publish.yml

@@ -0,0 +1,30 @@
+name: create-yorkie-app-publish
+on:
+  release:
+    types: [ created ]
+      # TODO(hackerwins): We need to decide how to publish create-yorkie-app.
+      # on:
+      #   workflow_dispatch:
+      #   push:
+      #     branches:
+      #       - main
+      #     paths:
+      #       - tools/create-yorkie-app/**
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout 🛎️
+        uses: actions/checkout@v2
+      - name: Setup Node 🔧
+        uses: actions/setup-node@v2
+        with:
+          node-version: '18'
+          cache: 'npm'
+          cache-dependency-path: package-lock.json
+          registry-url: 'https://registry.npmjs.org'
+      - run: npm install
+      - run: cd tools/create-yorkie-app && npm run build
+      - run: npm publish --provenance
+        env:
+          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}

examples/CONTRIBUTING.md

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+# Contributing
+
+See [CONTRIBUTING.md](../CONTRIBUTING.md) for the general guides for contribution.
+
+## Keeping create-yorkie-app in sync with examples
+
+When adding a new example, you have to update create-yorkie-app's [frameworks.ts](../tools//create-yorkie-app/frameworks.ts).
+
+Add FrameworkVariant to the variants array under appropriate category like:
+
+```js
+export const FRAMEWORKS: Array<Framework> = [
+  {
+    name: 'vanilla',
+    display: 'Vanilla',
+    color: yellow,
+    variants: [
+      {
+        name: 'vanilla-codemirror6',
+        display: 'codemirror',
+      },
+      {
+        name: 'vanilla-quill',
+        display: 'quill',
+      },
+      {
+        name: 'profile-stack',
+        display: 'profile-stack',
+      },
+      // Your yorkie example in Vanilla JS
+      {
+        name: 'directory-name',
+        display: 'display-name',
+      },
+    ],
+  },
+  // ...
+];
+```