Random local search over a set of permissible values

[HenrikMettler]

Addresses #373. This is based on an implementation I used in a project with hal-cgp, thus the default values for permissible-values. There is two open questions, marked as todo in the code comments.

For convenience i put a short example at the end. I can extend this to a full example before merging or remove it.

[HenrikMettler]

(CI-check fail seems like an unrelated mypy issue)