[clang] [libclang/python] Add a few things to the python api (PR #120590)

[Vlad Serebrennikov via cfe-commits]

Endilll wrote:

> @Endilll since there hasn't been a reply in months, do you think it's appropriate to close this?

Our existing practice is that PRs remain to linger like this until someone picks them up. Closing it would be "we don't want this" answer, and it wouldn't be correct.

That's how we end up with ever-growing number of opened PRs, yeah.

https://github.com/llvm/llvm-project/pull/120590