Add Github workflow checking formatting

.github/workflows/ensure-formatting.yaml

@@ -0,0 +1,19 @@
+name: ensure-formatting
+
+on:
+  pull_request:
+
+jobs:
+  ensure-formatting:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+        with:
+          submodules: recursive
+
+      - name: Test formatting for all files
+        working-directory: ${{ github.workspace }}
+        run: |
+          ./scripts/reformat-all.sh
+          [[ $(git status --porcelain | wc -l) == 0 ]]