[clang] Fix all mypy --strict errors in clang python binding (PR #101784)

[Jannick Kremer via cfe-commits]

DeinAlptraum wrote:

@TsXor thank you for your work!
I am generally all in favor of typing annotations, and I like that `ctyped` adds a stronger connection between the Python function definitions and the C library functions in terms of types.

That said, this PR is pretty massive and grows the Python bindings by about 800 lines of code (ignoring tests), which imo is quite a lot just to pass the strict type check. There are also a lot of refactoring and other changes in this PR that, while generally welcome, seem unrelated and should be factored out. In general, multiple smaller PRs are preferred over something of this size, to have clearer boundaries and ease reviewing.

For reference, I'd like to point out that I've also opened a PR for strict typing in #78114, which has been under review for a while.
With that out of the way: I'm still a very new contributor and since I've opened a PR for essentially the exact same thing, don't feel comfortable deciding on how to proceed with this. I'm summoning @Endilll: what are your thoughts on this?

https://github.com/llvm/llvm-project/pull/101784