Workaround for issues #518 #870

[AErmek]

This is just a workaround for issues #518 #870, not an official solution. And not tested on iOS devices.

I think these two issues are closely related to this audio_service 987 PR pull requests solution

[inludese]

This workaround will not work.
eventController already closed, because disposePlayer called and after that player?.release();

Future<void> release() async {
    eventController.close();
    await _audioHandler.stop();
  }