Clip transition animations within a task to the task

Freeform windows have task bounds. Activity transitions within
that task were poking out of the task bounds which looks weird.

This identifies when transitions are completely constrained to
a task and then will clip to the task instead of the stack.

Bug: 126751759
Test: atest AppTransitionControllerTest
      manual test: run settings and gmail in desktop.

Change-Id: I6b7ca74058cdf620b04c1c55f10fe645006c5139