Merge: Friendz: fix missing music file

This PR moves the music file in the Chainz of Friendz project to the new location of Android specific resources (changed in #1952). This missing file crashed the app at launch on Android.

Also use a Nit constructor/factory to wrap the static Java function `MediaPlayer.create` which is a convenience method acting as a constructor and applying some of the boilerplate code.

Pull-Request: #2004
Reviewed-by: Jean Privat <jean@pryen.org>