BroadcastQueue: misc bookkeeping events for OS.

This change brings over the remaining bookkeeping events that other
parts of the OS expects, such as allowing background activity starts,
temporary allowlisting for power, more complete OOM adjustments,
thawing apps before dispatch, and metrics events.

Fixes bug so that apps aren't able to abort broadcasts marked with
NO_ABORT flag.

Tests to confirm all the above behaviors are identical between both
broadcast stack implementations.

Bug: 245771249
Test: atest FrameworksMockingServicesTests:BroadcastQueueTest
Change-Id: If3532d335c94c8138a9ebcf8d11bf3674d1c42aa