Add stubs for static analysis (PR accepted?)

[Zocker1999NET]

I haven't found any stubs with type hintings for libzfs (neither here nor as 3rd-party package), so that static analysis tools like mypy can validate code which uses this library.

I'm currently writing a stubs file while developing a Python tool. So my question is if this project would accept a stubs file for libzfs? Then I would try to complete mine as good as possible and create a PR.