Update top resumed activity and focused app while adding a task on top

Drag to dismiss a split pair reparents the task on non-dismissing side
to the top of its TaskDisplayArea. The focused app should be updated if
the task on dismissing side was top focused.

This makes sure to update top resumed activity when adding a task on top
of a TaskDisplayArea. Also makes sure to update focsued app and last
resumsed activity in AMS while updating top resumed activity.

Fix: 242141128
Test: check mFocusedApp in dumpsys with repro steps of the bug
Test: atest ActivityTaskSupervisorTests
Test: atest ActivityRecordTests TaskDisplayAreaTests
Change-Id: I2dd0ca73df9c46ffce42cfc52280be35aeb9e2ec