[Partial Screenshare] Respond to task changes

Destroying the MediaProjection notifies the client app through the
MediaProjection callbacks that the app should handle the session
ending prematurely.

This may happen if setting up task recording failed, or if the
user exited the task that is being recorded.

Registering a listener to the task for configuration changes
also enables handling of the task entering/exiting split
screen.

Fixes: 219761722
Fixes: 237526949
Fixes: 236971595
Test: atest WmTests:ContentRecordingControllerTests
Test: atest WmTests:ContentRecorderTests
Change-Id: I415fb70433a031889f0486e99bb7d3b664333414