Allow touches through Taskbar when dragging to home screen

Setting visibleInsets to (almost) empty ensures the drag
events get sent to launcher.

Test: Drag a taskbar item on home, ensure it moves when
events are within the taskbar insets

Bug: 182079330
Bug: 171917176
Change-Id: Ida6a4a94a3fd2927d18245f45ed3e8d1701b9833