Ultimaker Robot Supported

Originally designed by Curt Roth, this Ultibot has been included as a standard file in a lot of Cura releases. It had been removed during a rebrand but it still has a special place in the heart of a lot of employees.

It even has its own dedicated page on [the Ultimaker website](https://ultimaker.com/nl/careers/ultimaker-robot) highlighting the different places where you can still find this robot.

The original file, [which still can be found in the source files](https://github.com/Ultimaker/Cura/blob/main/resources/meshes/UltimakerRobot_support.stl), is not watertight. This version has been fixed and made solid, so you don't see the error when loading this file.