Add persistent state for Bluetooth high quality audio support

This CL implements the storage/retrieval of flags for whether Bluetooth
A2DP sink devices support optional codecs and if they should be turned
on when that device is connected. It also contains code to listen for
device connections and do two things: (1) save whether that device
supports optional codecs, and (2) either enable or disable those codecs
for playback if we had a stored preference for the device.

Bug=37441685
Test: manually

Change-Id: I5f3113342d53aeeb9ede68602da8c7ff8c853457