Add fastlane for app stores

Please add fastlane which is useful for publishing on Google Play but required for publishing on F-Droid, see https://gitlab.com/fdroid/rfp/-/issues/3232#note_2665141185

For example implementation, see https://github.com/Beldex-Coin/bchat-android/commit/5ad09c9c8468410188827904898f0740ce16d70c

See also https://github.com/Beldex-Coin/bchat-android/issues/80