Apply transaction when starting back nav

The transaction was not applied anymore after the refactor and the
end of animation callback was not correctly set.

Bug: 228202811
Test: com.android.server.wm.BackNavigationControllerTests#backNavInfo_HomeWhenBackToLauncher

Change-Id: Id4635f2988a23ad7e214fb37739ba8dc2c394ee4
3 files changed