Add protobuf linter

.github/workflows/.protolint.yaml

@@ -0,0 +1,25 @@
+---
+name: Lint and Check Breaking Changes
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Buf Init
+        uses: bufbuild/buf-setup-action@v1.9.0
+        with:
+          version: latest
+      - name: Buf Lint
+        run: |
+          buf lint
+...