fix(typing): Reduce number of Unknowns in public APIs.

[elenakrittik]

Summary

Reduces the amount of unknown types in public-facing APIs. Intended to improve experience with disnake when using pyright in strict mode. I intentionally didn't go too deep and only focused on untyped *args/**kwargs here since they are (from my experience, at least) one of the most common untyped things when using disnake.

Checklist

• If code changes were made, then they have been tested
  • I have updated the documentation to reflect the changes
  • I have formatted the code properly by running pdm lint
  • I have type-checked the code by running pdm pyright
• This PR fixes an issue
• This PR adds something new (e.g. new method or parameters)
• This PR is a breaking change (e.g. methods or parameters removed/renamed)
• This PR is not a code change (e.g. documentation, README, ...)

[shiftinv]

thanks!