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

[Jannick Kremer via cfe-commits]

https://github.com/DeinAlptraum commented:

Hi and thanks for the PR!

To keep our history readable, please this up into smaller more focused PRs with an appropriate title ("Add a few things" won't be accepted ;)). This could be split into e.g. additions to the `File` interface, additions to the `Cursor` interface, and then type annotation(s).

If you add interfaces, please also add tests for them. `has_attrs` is also missing a doc string.

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