Check PendingStartActivityUids list before updateOomAdj is done.

While starting activity, WindowManager posts a runnable to DisplayThread to updateOomAdj.
The latency of the thread switch could cause client app failure when the app is checking
ActivityManagerService.isUidActive() before updateOomAdj is done.

Use PendingStartActivityUids to save uid after WindowManager start activity and before
updateOomAdj is done.

PendingStartActivityUids list is checked in
ActivityManagerService.isUidActive() and
AppOpsService.UidState.evalMode(). A uid in this list is treated same as
uid is active.

Bug: 157180494
Test: atest cts/tests/app/src/android/app/cts/ActivityManagerCameraLaunchTest.java
Change-Id: If0685c3c2fad01e48f3fcf2228057041f4ec9b00