AVRCP Controller manage active device

If multiple AVRCP devices are connected via bluetooth, manage the active
device based upon the recent browsing commands or playback state
changes.

Bug: 132642754
Test: atest AvrcpControllerStateMachineTest
Connect 2 phones and initiate playback from both remote devices as
well as browsing service.

Change-Id: I3384846ddb083cd103885ddc2f65e5018914b405