Adding support for LauncherAppWidgetHostView in CellLayout

With the introduction of LauncherAppWidgetHostView, CellLayout
no longer reorder correctly when dragging a widget.

Fix: 221495448
Test: When dragging a widget and all spaces are occupied, other icons
should move to the place the widget being dragged used to occupy.

Change-Id: I59ab21eb2717b56a216900049bb4546504e773ba
1 file changed