tools: always warp with the warp tool
Instead of warning the user that they can't erase or smooth a warp, the tool behavior is changed to Move.
Then the user can always warp, when GIMP starts up in Erase or Smooth mode and when the warp has been committed.
This: Move -> Erase -> Commit -> Move
Not this: Move -> Erase -> Commit -> GUI Stuck Warning -> Move