Bass: Handle empty broadcast receive state using previous source ID

That is necessary to properly handle empty receive state in remove
source cases independently of remove request source.

Add sending notifySourceRemoved with REASON_REMOTE_REQUEST.

Removed setting of source IDs. According to the documentation,
this is the responsibility of the remote. Setting artificial source
IDs on host side could cause an issue where remote had more than one
receive state characteristic.

Add sending notifySourceAdded with REASON_REMOTE_REQUEST when it is
read from remote or added later by remote without host request.

Refactored processBroadcastReceiverState to make it more readable.

Bug: 372322278
Bug: 380231464
Test: atest BassClientServiceTest BassClientStateMachineTest
Change-Id: I77dc65b7bb0124e463ec3e82794ca7683af192ed