Add linting CI

.github/workflows/check-format-and-lint.yaml

@@ -0,0 +1,26 @@
+name: Check formatting and lint
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Restore dependencies
+        run: dotnet restore
+      - name: Lint
+        run: |
+          npm ci
+          npm run lint
+
+          git diff
+          if [[ `git status --porcelain` ]]; then
+            exit 1
+          fi