Refresh group_type after saving

When using the form-designer and saving, the UFGroup.group_type is computed and stored on the server, but the old group_type is retained on the client. This could affect filtering of the dropdowns.

The new group_type isn't provided by the return for the API call to UFGroup.create – because it's not really computed until finishing the chained call to UFField.replace.

Maybe we could add another request to the API chain – a final UFGroup.get call? Then we would use the result from that to update the in-memory UFGroup.