Introspection: Adds basic input type annotations

[Tpt]

Implementation notes:

• The type annotation is a plain string. Indeed, it is not possible at my knowledge to properly concatenate strings from const code (hence without macros), making advanced structs not possible. Moreover, because it is not possible to use generic types in const code, we won't be able to generate list[int] types at the moment but only list. This limitation will be lifted if min_generic_const_args unstable feature lands at some point. However it should be possible to write a macro that validates the types and wrap them in some TypeAnnotation(&'static str) struct. Note that because our macros are aware of the Option<T> parameters annotations like T | None are properly generated. We might expand that to other common containers like Vec or HashMap.
• The stub generator autogenerates import with very naive code. I am not sure we want to keep autogenerating them with I fear more complexity or request the user to write them by hand. If we auto generate them we must make it more robust (maybe in a follow up?)
• The stubs generator does not support maximum line length yet, the test now reformats the stubs before doing string equality
• I have only written types for a few built-in elements to not overload this MR
• I have not added test coverage of types generated from #[pyclass]. We will get that for free after merging Implements basic method introspection #5087
• The default when no type is set is typing.Any. It might be cleaner to make INPUT_TYPE an Option<&'static str> and use None as the default value to not set an annotation instead.

[davidhewitt]

Sorry for the slow-ish review by me. I guess we will miss the 0.25 release for this (my bad).

Overall looks great, with just a few suggestions. 👍

[Tpt]

Thank you for the review.

I guess we will miss the 0.25 release for this (my bad).

There is still a bunch of follow ups to get something working properly so it's definitely not a big deal.

[davidhewitt]

Thanks, given all the comments I think this is good to merge (and I guess I can rebase the 0.25 branch to include this after all 😂)

[Tpt]

Thanks, given all the comments I think this is good to merge

Amazing!

(and I guess I can rebase the 0.25 branch to include this after all 😂)

I would feel better to have it in 0.26 to get time to do more testing, add more types across the codebase, deprecate the input_type and output_type methods...

[abrisco]

@Tpt seems like there was a conflict introduced in the merge queue for this one?

[Tpt]

@abrisco Yes! Rebasing this MR encovered some edge cases I have not considered (Self in signatures and PyO3-only magic methods like __traverse__). I hope to find some time soon to fix them.

[Tpt]

Rebase done. CI semverchecks is failing because this MR introduces a new associated constant to traits

The relevant bit to review 42c0cc6

[Tpt]

@davidhewitt This MR would love a second review after the rebases. The relevant additional commit is 42c0cc6

[davidhewitt]

Thanks, overall this looks good to me with one closing thought.

[Tpt]

Thank you for the review!

[davidhewitt]

Thanks, LGTM!