Creating a small client with the REST-API

[WolframPfeifer]

This is a placeholder issue for a topic of the 3rd HacKeYthon, where the idea is to create a small demonstrator (probably in Python) which implements a ping-pong game between and KeY and LLMs for specification inference/generation. The goal is to extract certain information from KeY, for example information about the open branches after a verification attempt, via the REST-API.

The work will build on #3303.

[samysweb]

Results in #3567 (now merged into #3303).
I'm not sure if it makes sense to leave this issue open?