AudioService: fix A2DP (dis)connection during media playback

  Fix issue with A2DP connection/disconnection during media
playback by modifying:
- how messages related to A2DP connection/disconnection are
  removed from the AudioDeviceBroker message handler: have
  .equals() be used when checking which object to remove,
  and correct which class is used for the messages in the
  queue:
    * MSG_IL_SET_A2DP_SINK_CONNECTION_STATE_*CONNECTED is
      using BtHelper.BluetoothA2dpDeviceInfo
    * MSG_L_A2DP_DEVICE_CONNECTION_CHANGE_EXT_CONNECTION
      is using BtDeviceConnectionInfo
- locking: use the AudioDeviceBroker main lock, mDeviceStateLock
  to synchronize posting events on the handler, and removing
  some of those messages to avoid race conditions the thread
  in which events are posted (e.g. BT's event thread) and the
  AudioDeviceBroker handler thread.

  Cleanup: annotation around audio formats from native defined
in AudioSystem, moved conversions to AudioSystem.

Bug: 142293357
Test: atest AudioDeviceBrokerTest
Change-Id: I2e8dc813354829fb1b2c7ca95ad395a14f8b70cf