Add codegen check workflow (#347)

Make sure that the generated clients are up to date.

.github/workflows/check-codegen.yml

@@ -0,0 +1,26 @@
+name: Check Codegen
+
+on:
+  pull_request:
+    paths-ignore:
+      - 'docs/**'
+      - '**/*.md'
+
+jobs:
+  check-codegen:
+    runs-on: self-hosted
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-go@v2
+        with:
+          go-version: '1.17'
+      - name: Run make generate
+        run: make generate
+      - name: Compare the expected and actual generated/* directories
+        run: |
+          if [ "$(git diff --ignore-space-at-eol generated/ | wc -l)" -gt "0" ]; then
+            echo "Detected uncommitted changes after build. Consider running 'make generate'."
+            echo "See status below:"
+            git diff
+            exit 1
+          fi