Volume change intent carries stream alias

Define a new extra, AudioManager.EXTRA_VOLUME_STREAM_TYPE_ALIAS, to be
  sent along with the volume change intent, VOLUME_CHANGED_ACTION.
When sending VOLUME_CHANGED_ACTION, attach the stream type alias.

Bug 17955277

Change-Id: I04fd279e223504e3ee1581086d7e9205344a6808