Add APIs for setting preferred mixer attributes.

This is part of improving USB audio improvment. With setting preferred
mixer attributes, the apps will be able to pick the best configuration
for their playback. That can help avoid data conversion so that the apps
can provide best audio experience and improve latency.

Bug: 239435816
Test: atest AudioManagerTest
Change-Id: I6c930a53c4071e5426be1c6dd3ccb6a999de214d