fuzzy testing with pysource_codegen

[15r10nk]

Description

This pull-request adds fuzzy testing with pysource_codegen and pysource_minimize

Bugs found so far:

• #3678
• #3677
• #3676

Checklist - did you ...

• [ ] Add an entry in CHANGES.md if necessary?
• [ ] Add / update tests if necessary?
• [ ] Add new / update outdated documentation?

[hauntsaninja]

Thanks for writing this tooling! Since those bugs are now fixed, we could try adding this to CI for real?

[15r10nk]

@hauntsaninja yes, I think it would be a good idea to integrate it into the CI, but ...

I rebased this branch and it took me 3 seconds to find another issue.

class name_5[name_4: lambda: something]:
     pass

I reported it #4599.