Check that the /build/ folder compiles and all `.js` is checked in (#141653)

.github/workflows/check-clean-git-state.sh

@@ -0,0 +1,6 @@
+R=`git status --porcelain | wc -l`
+if [ "$R" -ne "0" ]; then
+  echo "The git repo is not clean after compiling the /build/ folder. Did you forget to commit .js output for .ts files?";
+  git status --porcelain
+  exit 1;
+fi

.github/workflows/ci.yml

@@ -298,6 +298,12 @@ jobs:
       - name: Run Valid Layers Checks
         run: yarn valid-layers-check
 
+      - name: Compile /build/
+        run: yarn --cwd build compile
+
+      - name: Check clean git state
+        run: ./.github/workflows/check-clean-git-state.sh
+
       - name: Run eslint
         run: yarn eslint