Animation for Freeform -> Fullscreen Transition

When dragged into the status bar, the task will animate to fullscreen
via shell transition.

Video: https://recall.googleplex.com/projects/099cef64-5403-42f3-bc17-ea11eb878bba/sessions/2f77cbf6-5c2b-4784-a51d-30a913eab75d

Bug: 266973675
Test: Manual; drag caption into status bar from various starting sizes.

Change-Id: Ie542676530c630bd1f31d769b050b09603291074