Move RIMSEvalGUI repo into this repo

[trappitsch]

Well, maintainability hasn't been great in order to keep the GUI in its own repository. Thus, it should really move in here. A demo of this has already been shown with the DigOutBox. This migration will need a few considerations:

• Keep the structure of the repo and just move it to a subfolder at the beginning / as long as fbs is used for packaging
• Set up rye workspace that installs the GUI into the venv
• Packaging with fbs: How will that work? It might not be all that great.
• Version numbers between rimseval and the GUI: Do we keep them separate with some useful rules (see, e.g., guide for digoutbox) or do we synchronize them up?

One idea is to move the whole GUI with packaging over to box, but details need to be specified and should be discussed somewhere else.