Feat: Expand **kwargs with field names on hover when `**kwargs` is typed with `Unpack` (i.e. `**kwargs: Unpack[T]`)

[michaelfortunato]

Say a function has a parameter **kwargs and its typed with Unpack. On hover it would be nice if **kwargs was replaced with the actual argument names and their types.

For instance, in the screenshot below, hovering on func reveals two arguments, arg1 and **kwargs. It would be nice if instead hovering on func showing arg1, extra_arg1, and extra_arg2.

Thanks.

[connernilsen]

Hey @michaelfortunato, thanks for suggesting this it seems like a useful idea! @kinto0, what do you thinkg, and should this be a good-first-issue or help-wanted task?

[kinto0]

I'm not entirely sure what this entails since I don't really know anything about typeddicts. So probably not a good-first-issue if I'm the one doing code review.

For reference, Pylance doesn't handle this either:

[yangdanny97]

@kinto0 in your screenshot having expansion logic would render the function as: def func(*, a: bool = ..., b: int = ...)

ie: the fields get expanded into kw-only args, and any NotRequired fields have defaults so they're optional.

this is useful for when unpacked typeddicts have required fields, since then you can see what you're missing.