Move appop watcher logic into AppOpsService

The interface is intended to be for queries about the raw data state.
We also remove the foregroundOps cache that is used for dispatching
foreground mode changes; since we now have to do more computation on
foreground changes to dispatch callbacks the performance impact has been
briefly analyzed to show that onUidStateChanged is not a highly
frequently called method and went from .05ms to 0.07ms to execute. This
was calculated by running CtsAppOpsTestCAses and tracing.

Test: atest CtsAppOpsTestCases
Fixes: 268696066
Change-Id: I96700653496984aa3333b174abf2ceb3c1790b10