Always go to next source in player and add thread safety

[Luna712]

We don't want to ever kick out of the player if the first source fails, we can just show the unknown error toast and still go to the next source for more stable error handling. In the future we can still expand the different types of toasts shown to be clear about what the error is, but in reality we should never just kick out of the player if the first source is an error and there are other sources.

This also adds thread safety, and fixes issues with context required on the UI thread. Before lint couldn't follow ioSafe or other custom Coroutines methods, but this adds annotations to tell lint to follow properly ensuring proper build failures with WrongThread should it be called on the wrong thread.

For example with context:

Error: Method getContext must be called from the UI thread, currently inferred thread is worker thread

Is now given if called on the wrong thread. Doing it like this also would have caught other issues in the past as well.

Also, androidx.annotation:annotation is fully KMP compatible so has no issues with being in commonMain in library either. Just for consistency to ensure we always use the same version, it is also added explicitly to the app module.

[fire-light42]

The idea of this is to handle irrevocable and unknown errors by simply exiting the player, and can be seen as a soft app crash. If we do not know what happen, the system may have been left in a bad state causing worse problems than if we did not exit.

This is the general java philosophy, but I can see why it may cause user friction. Especially given that no such problem is realistically expected to happen.