Add a workflow to build btbench

.github/workflows/gradle-btbench.yml

@@ -0,0 +1,33 @@
+name: Gradle Android Build & test
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+    paths:
+      - 'extras/android/BtBench/**'
+
+permissions:
+  contents: read
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    timeout-minutes: 40
+
+    steps:
+      - name: Check out from Git
+        uses: actions/checkout@v3
+
+      - name: Set up JDK
+        uses: actions/setup-java@v4
+        with:
+          distribution: 'zulu'
+          java-version: 17
+
+      - name: Setup Gradle
+        uses: gradle/actions/setup-gradle@v3
+
+      - name: Build with Gradle
+        run: cd extras/android/BtBench && ./gradlew build