Don't abort transition for activity re-ordering.

ActivityStarter will reorder activities and change their
visibilities but still report DELIVERED_TO_TOP. This means
we need to do some secondary checks for whether the top
changed. This adds some additional tracking so that we
don't abort the transition if activity visibility does
change.

Bug: 243812111
Test: wmtest ActivityStarterTests
Change-Id: I14e42b55cc95b9331d1dbc1afb5da1457acedf9d