BroadcastQueue: pre-calculate blocked counts.

In an upcoming change we're going to try relaxing setDeliveryState()
to only invalidateRunnableAt() for processes that have just been
unblocked by the operation that just finished.

To enable that shift, we'll need blockedUntilTerminalCount access
at the BroadcastRecord level, so this change shifts to calculating
it when we create the BroadcastRecord; this also saves an extra
traversal of the receivers list to derive the "prioritized" boolean.

Bug: 253906105
Test: atest FrameworksMockingServicesTests:BroadcastRecordTest
Test: atest FrameworksMockingServicesTests:BroadcastQueueTest
Test: atest FrameworksMockingServicesTests:BroadcastQueueModernImplTest
Change-Id: Ie689360d4f2c7af7d936259d9dfa05f663f450a8