Use GestureDetector in WorkspaceTouchListener

Replace the current callback logic in WorkspaceTouchListener with the
use of GestureDetector.
Platform-provided api will now be used  for detecting long press.

Test: long press on empty home screen
Bug: 126596502
Change-Id: I5beb9158ee0d9ec6ac031465f15923eed2d5f066
1 file changed