feat: Add option to search for stubs packages

[romain-intel]

This allows using the feature in griffe that searches for stubs packages

Related: mkdocstrings/griffe#221

[romain-intel]

I think this should work. Will play with it a bit but wanted to open something so I don't forget. Hopefully it's as simple as this :). Let me know and happy to fix any issues.

[pawamoy]

Nice, thanks!

Are you planning to only use this config option along with preload_modules? I suppose other users would want to use it directly, without having to specify other modules to preload? Then we should also add find_stubs_package=final_config["find_stubs_package"] to the next line (285 here).

Could you also add an entry in the documentation? In docs/usage/configuration/general.md. No need for previews here, just an explanation of what this does, with file layouts (you can use tree fences).

I can also take it from here if you don't have the capacity 🙂

[romain-intel]

Oops, I want to use it in line 285 so yes, I will add it there directly as well (that was an omission). I'll look for the doc and add it. No problem. Thanks for taking a look. I'll do this tonight.

[pawamoy]

Thanks, looking good!