Implement CI/CD for Android (#48)

* Implement CI/CD for Android with Fastlane

mobile/android/fastlane/Fastfile

@@ -0,0 +1,25 @@
+# This file contains the fastlane.tools configuration
+# You can find the documentation at https://docs.fastlane.tools
+#
+# For a list of all available actions, check out
+#
+#     https://docs.fastlane.tools/actions
+#
+# For a list of all available plugins, check out
+#
+#     https://docs.fastlane.tools/plugins/available-plugins
+#
+
+# Uncomment the line if you want fastlane to automatically update itself
+# update_fastlane
+
+default_platform(:android)
+
+platform :android do
+
+  desc "Update AAB to PlayStore"
+  lane :beta do
+    upload_to_play_store(track: 'beta', aab: '../build/app/outputs/bundle/release/app-release.aab')
+  end
+
+end