Create a workflow for building android apk

.github/workflows/build_android.yml

@@ -0,0 +1,25 @@
+name: Build Android
+
+on:
+  workflow_dispatch:
+  push:
+    branches: [ "main" ]
+    paths:
+      - 'Android/**'
+  pull_request:
+    branches: [ "main" ]
+    paths:
+      - 'Android/**'
+
+jobs:
+  build_apk:
+    name: Build APK
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: ./Android
+    steps:
+      - name: Checkout the source code
+        uses: actions/checkout@v3
+      - name: Build
+        run: ./gradlew assembleRelease