[CI] Adds Code Generation tests on Github Actions (#6482)

Moves check-grpc-generation to scripts

scripts/check-grpc-generated-code.sh

@@ -0,0 +1,32 @@
+#!/bin/bash
+#
+# Copyright 2021 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+set -e
+
+echo "Checks generated grpc code"
+cd grpc/examples
+sh generate.sh
+cd ..
+
+if ! git diff --quiet; then
+  echo >&2
+  echo "ERROR: ********************************************************" >&2
+  echo "ERROR: The following differences were found after running the" >&2
+  echo "ERROR: grpc/example/generate.sh script. Maybe you forgot to run" >&2
+  echo "ERROR: it after making changes in a generator or schema?" >&2
+  echo "ERROR: ********************************************************" >&2
+  echo >&2
+  git diff --binary --exit-code
+fi