Only reset the frozen recents list if touching outside of the mandatory system gesture region

- Currently, any touch after a quickswitch within an app window will be
  construed as a reset of the frozen task list, however we allow users
  to quickswitch multiple times whenever touching within the mandatory
  system gesture region, so we should also ensure that touches within
  that region are also ignored.
- Also add protologs for when we set/reset the frozen list

Bug: 320408763
Test: Quickswitch, but touch above the nav handle and within the
      system gesture region, verify this does not trigger resetting

Change-Id: Ie8dd880eb2b45812d5b72ec1ae1c23e28ba02250
Signed-off-by: Winson Chung <winsonc@google.com>