Add PR Validation (#1)

Author: nguerrera

.github/workflows/pull-request.yaml

@@ -0,0 +1,34 @@
+name: Cadl PR Validation
+on: 
+  pull_request:
+    branches: [master]
+    
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-node@v2
+        with:
+          node-version: '14'
+
+      - run: node common/scripts/install-run-rush.js install
+        name: Install JavaScript Dependencies
+
+      - run: node packages/cadl-vs/scripts/build.js --restore
+        name: Restore .NET Dependencies
+
+      - run: node common/scripts/install-run-rush.js check
+        name: Check For Dependency Version Mismatches
+
+      - run: node common/scripts/install-run-rush.js rebuild --verbose
+        name: Build
+
+      - run: node common/scripts/install-run-rush.js test-official
+        name: Test
+
+      - run: node common/scripts/install-run-rush.js check-format
+        name: Check Formatting
+
+      - run: node eng/scripts/check-for-changed-files.js
+        name: Check Git Status For Changed Files