Put recents input consumer to the top of the display area

- Instead of trying to place it above the top task which can't account
  for other relative layering (ie. IME), just place the consumer at
  the top of the display area containing all the tasks

Fixes: 195427335
Fixes: 198416276
Test: Open an app with the IME showing, enter recents
Change-Id: Iab9ccea417b1c14d8318296ee8bc181528942013