Use correct task bounds when moved from fullscreen to freeform stack

When we are moving a task to the freeform stack, get the launch bounds
to use or layout in stack vs. using the existing bounds that can be
null.

Also, prevent moving a task to the freeform stack if freeform isn't supported.

Bug: 27157914
Change-Id: I0d86baa6141961b92a436107b5c5bb1316570558