FreeformHandler should just intercept, not claim animations

There are already animations for most of these operations (eg. in
launcher), so instead of "claiming" the transition animation
and doing nothing, this should just update state (window decor)
and then let other handlers play the animations.

Bug: 241486751
Test: launch app from launcher, go back.
Change-Id: Ic5d01b76c04d6adab484d53d24d1a89b001a4c80