Add TaplTestsQuickstep#testExcludeFromRecents

- Add ExcludeFromRecentsTestActivity, and add it to the manifest
  with excludeFromRecents="true"
- Add the test to check the current Overview task content
  description, ensuring that the excludeFromRecents task is
  present directly after a gesture but not after going home.
Bug: 324495241
Flag: None
Test: TaplTestsQuickstep#testExcludeFromRecents

Change-Id: I06be53673f0ac06924f79b44f19744da066cc7ea