Type openpyxl functions module and its usages

[Avasam]

Split off from, and improved over, #9511

• Typed openpyxl functions module and its usages
  Typing this module is kind of a real mess, in-code comment should explain it well. Since we can't really use any other xml libraries in these stubs anyway for various reasons (untyped, not a dependency, ...), xml is the only compatible one for typing openpyxl.
• Still I tried to use sensible Protocols when possible. For that reason I also moved some shared protocols from nested.pyi.
• Created _functions_overloads.pyi to abstract away most of the complexity and re-implement overloads of the different possible libraries.
• Updated the stubtest_allowlist

[srittau]

We try to avoid IO etc. in typeshed if possible. Is it possible to use a protocol here?

[Avasam]

Yeah, the close and write methods are used. (Maybe more I'll double check usage in other parts of the code)
If the out parameter is None, it seems to default to a BufferedWriter and IO was the top parent with both methods.

[Avasam]

I simplified it down to StrPath | str, I changed it to StrPath with an additional union to BytesIO because there's an explicit if isinstance(self.out, BytesIO) branch in WorksheetWriter.read.

[AlexWaygood]

StrPath is a union that already includes str, no?

[Avasam]

uh, yes, lemme simplify that too real quick ^^

[Avasam]

Looking at the et_xmlfile implementation of xmlfile, if not passing directly a string, it needs the close and write method. But that one isn't restricted to BytesIO. Maybe I should just replace BytesIO in that union with a protocol that has both methods and that BytesIO can match.

[srittau]

LGTM, at least as a first stab. Original code is a mess, so let's see whether there are any problems in the future.

[srittau]

Yikes, that code is a mess in the original source code. So if I read this correctly, WorksheetWriter.read() only works with BytesIO and whatever can be passed to open() (str-like paths). .cleanup() work only with str-like paths. .get_stream() calls xmlfile(), where at least the lxml variant needs a "file-like object" or a string, according to the docs. And, if not supplied to the constructor, it's initialized to NamedTemporaryFile() (or its return value), which is neither a str-like path nor a BytesIO. Yeah, let's just use your solution for now.

[github-actions]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉