ci: add retries and caching for gradle installation (#34619)

This change uses Gradle's official `setup-gradle` action to allow the
caching of the downloaded gradle distribution and java dependencies in
the GitHub Actions cache. However, since the initial download of gradle
distribution is still handled by the `gradlew` wrapper script which
doesn't retry on network failures, this change also adds a simple retry
mechanism using shell scripting.

Fixes #34600

Signed-off-by: Mukilan Thiyagarajan <mukilan@igalia.com>

.github/workflows/android.yml

@@ -79,6 +79,14 @@ jobs:
         id: setup-ndk
         with:
           ndk-version: r26c
+      - name: Setup Gradle caches
+        uses: gradle/actions/setup-gradle@v4
+      - name: Trigger initial download of Gradle with retries
+        run: |
+          for i in {1..4}; do
+            ./gradlew --version && break || { echo "Downloading Gradle failed (attempt $i)." && sleep $((3 ** $i)); };
+          done
+        working-directory: ./support/android/apk/
       - name: Setup Key Store for APK Signing
         env:
           KEYSTORE_BASE64: ${{ secrets.APK_KEYSTORE_BASE64 }}