Fix detection of `LanguageServer` type annotation when future annotations are used

[zanieb]

Description

The following example fails on main because the annotation is a string rather than a concrete type due to the use of from __future__ import annotations. typing.get_type_hints can be used to resolve the annotations for the signature to support detection in this case.

from __future__ import annotations

from pygls import server

async def example(
    foo: server.LanguageServer,
    params: None,
) -> None:
    pass

from pygls.feature_manager import has_ls_param_or_annotation

assert has_ls_param_or_annotation(example, server.LanguageServer)

This can also be reproduced by wrapping the annotation type in a string manually (as I do in the test in this pull request).

Code review checklist (for code reviewer to complete)

• [x] Pull request represents a single change (i.e. not fixing disparate/unrelated things in a single PR)
• [x] Title summarizes what is changing
• [x] Commit messages are meaningful (see this for details)
• [x] Tests have been included and/or updated, as appropriate
• ~[ ] Docstrings have been included and/or updated, as appropriate~
• ~[ ] Standalone docs have been updated accordingly~
• [x] CONTRIBUTORS.md was updated, as appropriate
• [x] Changelog has been updated, as needed (see CHANGELOG.md)

[tombh]

Looks good ❤️

I'm happy to merge. But maybe @alcarney wants to give it a thumbs up too?

[tombh]

Thank you 🙇

[alcarney]

But maybe @alcarney wants to give it a thumbs up too?

Better late than never! :sweat_smile: Looks good!