Add workflow definition for smoke tests (#3960)

Author: yifanyang

.github/workflows/smoke-tests.yml

@@ -0,0 +1,59 @@
+name: Smoke Tests
+
+on: [ pull_request ]
+
+jobs:
+  smoke-tests:
+    if: github.event.pull_request.head.repo.full_name == github.repository
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 2
+          submodules: true
+      - name: Set up JDK 11
+        uses: actions/setup-java@v2
+        with:
+          java-version: 11
+          distribution: temurin
+          cache: gradle
+      - name: Set up NDK 21.4.7075529
+        run: |
+          ANDROID_ROOT=/usr/local/lib/android
+          ANDROID_SDK_ROOT=${ANDROID_ROOT}/sdk
+          ANDROID_NDK_ROOT=${ANDROID_SDK_ROOT}/ndk-bundle
+          SDKMANAGER=${ANDROID_SDK_ROOT}/cmdline-tools/latest/bin/sdkmanager
+          echo "y" | $SDKMANAGER "ndk;21.4.7075529"
+          ln -sfn ${ANDROID_SDK_ROOT}/ndk/21.4.7075529 ${ANDROID_NDK_ROOT}
+          echo "ANDROID_NDK_HOME=${ANDROID_NDK_ROOT}" >> $GITHUB_ENV
+      - uses: google-github-actions/auth@v0
+        with:
+          credentials_json: ${{ secrets.GCP_SERVICE_ACCOUNT }}
+      - uses: google-github-actions/setup-gcloud@v0
+
+      # TODO(yifany): make it a fireci plugin and remove the separately distributed jar file
+      - name: Download smoke tests runner
+        run: |
+          SMOKE_TESTS_RUNNER_URL="https://storage.googleapis.com/android-ci/smoke-tests-runner.jar"
+          curl ${SMOKE_TESTS_RUNNER_URL} --output runner.jar
+
+      # TODO(yifany): remove hardcoded reference to /smoke-tests-google-services from the runner
+      - name: Add google-services.json
+        env:
+          SMOKE_TESTS_GOOGLE_SERVICES: ${{ secrets.SMOKE_TESTS_GOOGLE_SERVICES }}
+        run: |
+          echo $SMOKE_TESTS_GOOGLE_SERVICES | base64 -d > google-services.json
+          sudo mkdir /smoke-tests-google-services
+          sudo mv google-services.json /smoke-tests-google-services
+
+      # TODO(yifany): remove hardcoded reference to Prow environment variables from the runner
+      - name: Run smoke tests
+        env:
+          FIREBASE_CI: 1
+          REPO_OWNER: ${{ github.repository_owner }}
+          REPO_NAME: firebase-android-sdk
+          PULL_NUMBER: ${{ github.event.pull_request.number }}
+          JOB_NAME: smoke-tests
+          BUILD_ID: ${{ github.run_id }}
+          ARTIFACTS: ${{ runner.temp }}
+        run: java -jar runner.jar smoke-tests/runner.config