BroadcastQueue: misc debugging, fix runnable bug.

Add new per-reciever fields to BroadcastRecord dump information, where
we have both "scheduled" and "terminal" timestamps.  Update legacy
stack to also record these timestamps for consistent dumps.  Update
modern stack to record overall dispatch and finish times.

Add "reason" behind per-process queue runnable calculation, aiding
debugging of why a process might be delayed or paused.  Simplify dump
of per-process queue to omit redundant details.

Fix subtle bug when skipping broadcasts, where we might need to update
sorted runnable list position if we modified the queue.  Consistency
check logic to help identify bugs.

Bug: 249389115
Test: atest FrameworksMockingServicesTests:BroadcastQueueTest
Test: atest FrameworksMockingServicesTests:BroadcastQueueModernImplTest
Change-Id: I73c442f749fba9c461a67debfa871ffcd0dda086