feat: Add common CI checks to be shared by all repos.

Author: iphydf

.github/workflows/ci.yml

@@ -0,0 +1,9 @@
+name: ci
+
+on:
+  pull_request:
+    branches: [master]
+
+jobs:
+  common:
+    uses: TokTok/ci-tools/.github/workflows/common-ci.yml@master

.github/workflows/common-ci.yml

@@ -0,0 +1,15 @@
+on: [workflow_call]
+
+jobs:
+  buildifier:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          submodules: recursive
+      - name: Install
+        run: |
+          wget -O buildifier https://github.com/bazelbuild/buildtools/releases/download/4.2.4/buildifier-linux-amd64
+          chmod +x buildifier
+      - name: Check
+        run: ./buildifier --lint=warn --warnings=all -mode diff $(find . -type f -name "WORKSPACE" -or -name "BUILD.*")