Add an inputconsumer override method for modern recents transitions

Shell transitions doesn't use RecentsAnimationController anymore.
Instead, its more structured to just inform inputmonitor when it
is and isn't animating recents. InputMonitor then can use this extra
information to reroute focus to the recents input consumer at the
right times.

Unlike legacy transitions, recents will actually be on top and get
preferred focus when active. However, the live tile will still be
drawn above it. This means we need to also provide InputMonitor with
the live-tile activity (the "reference" activity) so it can place
the recents inputconsumer at the right z-order.

Bug: 193565597
Test: atest ReOpenImeWindowTest
Change-Id: Iad37888789e14bc049b1a52dd5142eb6c3ea2e99