[REQUIRED] Use case description

When implementing a player that is not based on exoplayer, we need to handle becoming noisy, audio focus, and the wake management ourselves. Exoplayer has implementations for all these that I believe I could use in my player, but they are package private.

Proposed solution

Make AudioBecomingNoisyManager, WakeLockManager, and AudioFocusManager public. Or make a variant of SimpleBasePlayer that handles them.

Alternatives considered

my current solution is to copy these classes.