Audio focus API with AudioAttributes and more options

Wrap all options of an audio focus request into a new
 class, AudioFocus request, and the corresponding
 methods in AudioManager to request and abandon focus
 with an AudioFocusRequest instance.
New options include handler for focus change listener,
 delayed focus, and option for specifying pause behavior
 on duckable transient loss of focus.

Test: cts-tradefed run cts -m CtsMediaTestCases -t android.media.cts.AudioFocusTest
Bug: 30258418

Change-Id: I99151270d0d9c59595db3f5c91480c7af2d1fd71