Make Splash-screens touch opaque cross uid

Attempt 2. First attempt broke automated testing that started sending
input as soon as the ActivityWindow was created. Since there are a few
frames where both the SpalshScreen and the underlaying activity is
visible we let touches pass through the SpalshScreen to the underlaying
activity. However if the ActivityWindow doesn't exists the touches will
be blocked by the ActivityRecordInputSink.

This works thanks to the untrusted touches feature in InputDispatcher
that blocks touches that are passing through opaque layers if the layers
belong to different UIDs. By moving the ActivityRecordInputSink layer to
the framework uid and leaving the AcitvityWindow and the splashscreen
belonging to the application uid we achive the separtion we want:
SpalshScreen are touch opaque cross uid, but are non-touchable within
the same uid.

Test: atest CtsInputTestCases:android.input.cts.InputShellCommandTest
Test: Manually verified that touches will no longer pass through the
StartingSurface to the ActivityRecordInputSink
Bug: 194480991
Bug: 208659130
Bug: 211748378

Change-Id: I35ee6b40c108607c17dbf65fcd74656aec9c2a87