Create CallGraphCodemod

[Kludex]

I'll not merge this into fastapi-responses. I'll create another package, and then use it here

The idea is to first map all function definitions and calls that are inside of those.

[old-syniex]

Will it make the package depends on libcst?

[Kludex]

No. The idea here is a bit different than what it current does.

I'd like to transfer the runtime behavior into a tooling that can automatically add the exceptions information into the FastAPI endpoint decorator.