Allow granting BAL privileged by opt-in on Broadcast PendingIntent

The current logic assumes that the creator of the PendingIntent is also the target of the PendingIntent, and only creates a BAL token if the creator is different from the sender, while the receiver of the broadcast needs the BAL permission.
The logic to prevent apps from creating their own tokens is moved to `BroadcastQueueImpl'.

Test: atest BackgroundActivityLaunchTest
Flag: com.android.window.flags.bal_check_broadcast_when_dispatched
Bug: 421197489, 422788436
Change-Id: Iec7ca549e2ef7ae889d94625fac83f19c8e7f657