Pass through Recent's finish-but-not-really intent

There are a few situations where recents will tell WMCore
that it is finishing (going home), but then actually doesn't
finish. In these cases, we need to tell WMCore not to enter
PiP even when it normally would.

This functionality is added to shell-transitions by adding
a signal to WindowContainerTransaction.

Bug: 223317893
Bug: 223317556
Test: open pipable, go to recents, swipe pipable to close.
Change-Id: I969ae8b562aa54fc06e35164e676205682f24994