Introduce a flag removeWithTaskOrganizer.

- The flag allows us to remove the tasks which are managed by
  TaskOrganizer when TO dies.

Bug: 179676966
Test: Launch a Bubble, kill SysUi and check if the Bubble remains in
  ActivityStack.
Change-Id: Ie0ccafd2b4b0393b777b69b7fb70c0ea74f95963