Minor refactoring to the modern queue

Bug: 249161784

This contains some small changes to the modern queue to prepare for
larger changes with batched broadcasts.

 1. The BroadcastRecord is updated before it recorded in the history.
    This allows the history to make a copy and not miss any
    information.

 2. The logic in scheduleReceiverWarmLocked() is factored into
    separate methods that can be called from other code.

 3. finishReceiverLocked() takes an explicit BroadcastRecord and
    index.  The logic to continue scheduling receivers has been pulled
    out.

The changes are designed to have no functional effect.

Test: atest
 * FrameworksMockingServicesTests:BroadcastQueueTest

Change-Id: I4a154ebfa5c0f506d59fe81504e055366ed5fc81