fix: retain exoplayer on orientation change

[Pittvandewitt]

This PR is basically the last step of #6307
Now you should feel the improvement upon rotation change ;)

The ExoPlayer is no longer stopped on onDestroy, because it is already released in its viewmodel onDestroy method.

[Bnyro]

Wait, this would also mean that the current player video stays alive when the user closes a video and it still continues to buffer.

Apart from that viewModel.isOrientationChange already conditionally does what you're trying to achieve with this PR, doesn't it?

[Pittvandewitt]

When the video closes with PlayerFragment, PlayerViewModel is also destroyed and PlayerViewModel.onCleared is called, where the exoplayer is released. Or does ExoPlayer.stop also need to be called before ExoPlayer.release?

With this PR I notice no interruption when changing orientation, but with the current implementation of viewModel.isOrientationChange I always do, especially when pressing the full screen button.

[Bnyro]

When the video closes with PlayerFragment, PlayerViewModel is also destroyed and PlayerViewModel.onCleared is called,

You're right, I thought that would only be called in the activity's onDestroy and not in the fragments, but I tested it and it looks like you're right.