Add parameter to save task snapshot when it is requested

- In legacy recents animation, the snapshot requested is also saved to
  the task snapshot cache, which triggers a subsequent notification to
  Launcher and updates the cached snapshot sent to AiAi for smart
  select. This change just adds an option to the existing call to allow
  the caller to request that the snapshot is saved to trigger the same
  path.

Bug: 276340272
Test: Open Chrome, scroll a bit, swipe up to overview and trigger smart
      select
Change-Id: I5364f42d9ddc5f3ed67def19c9e9944279591e58