Updating the preview generation logic so that it aligns better with

the drag source image

> Using common code for pending item drag (WidgetContainerView and PinItemDragListener)
> Adding a shortcut-circuit in Workspace when a pendingItem can create a shortcut
  directly. Previously the multi-window drop was routing through onActivityResult which
  was causing some state information to be lost.

Bug: 33584624
Change-Id: I0259870032185713caa9bff27092dbae6ce91199