Switch activity state pushing to ConcurrentLinkedQueue

Activity state changes are time sensitive and updating
ProcessStateController too slowly can cause unexpected behavior.
Migrating the activity state pushing from being posted on a Handler
thread to a ConcurrentLinkedQueue enables ProcessStateController to
oppurtunistically handle the state changes without waiting for the
associated update.

Example of bad behavior due to slowness:
The CameraEvictionTest#testCamera2AccessCallbackInSplitMode test fails
because it has some fairly tight expectation about CameraAccessPriority
timeliness (which is based off of ProcState and OomScore changes)

Flag: com.android.server.am.push_activity_state_to_oomadjuster
Bug: 401350380
Test: atest MockingOomAdjusterTests
Test: atest ProcessStateControllerTest
Test: atest android.hardware.multiprocess.camera.cts.CameraEvictionTest#testCamera2AccessCallbackInSplitMode

Change-Id: Ia50a98fb5c51b386f199f5f689bf8a3fe155e607