Ensure recents input consumer can be focused in Overview

- Previously, when a fix for b/138622418 was introduced, it also changed
  the behavior to make the windows being animated by recents
  not-touchable, which caused additional checks on the input monitor
  side to handle this case.  But because we already have the recents
  input consumer in place to intercept input, we can leave the window
  touchability as is (as we do in other cases like PIP where we also
  intercept all input), and rely on the existing behavior in input
  monitor to focus the consumer if one of its animating windows is
  focused.

  To not regress on b/138622418, we push the check up to where the
  window is considered for affecting the exclusion rects instead.
  This enabled the followup CL of routing the back gesture to the
  consumer with the new back flow.

Bug: 223750399
Test: Verify b/138622418 - swipe up from home and quickly swipe to
      -1 and ensure back doesn't show
Test: Verify b/191058092 - receive a HUN while in overview and ensure
      input focus switches from recents input consumer -> notif shade
      and IME shows, and then back to the input consumer when finished
Test: Verify b/177923822 - recents input consumer is always focused
      in overview in all nav modes and volume works and is routed to
      launcher to handle


Change-Id: I79160004afc7d6759563ef68a9e2a480ef3d900a