feat: Implement better get_or_fetch

[Lumabots]

Summary

Information

• This PR fixes an issue.
• This PR adds something new (e.g. new method or parameters). Implement better get_or_fetch #1856
• This PR is a breaking change (e.g. methods or parameters removed/renamed).
• This PR is not a code change (e.g. documentation, README, typehinting,
  examples, ...).

Checklist

• I have searched the open pull requests for duplicates.
• If code changes were made then they have been tested.
  • I have updated the documentation to reflect the changes.
• If type: ignore comments were used, a comment is also left explaining why.
• I have updated the changelog to include these changes.

[Lumabots]

feat from #1856

[Lumabots]

still not ready have some bug like : NameError: name 'VoiceChannel' is not defined
ig because of the type checking, i'll have to find a way to import it without circular import

[Paillat-dev]

@Lumabots You can import it inside of the function where you use it directly instead of importing it at the top

[Lumabots]

@Lumabots You can import it inside of the function where you use it directly instead of importing it at the top

Well ig the issue come from the definition for the typevar, so will that resolve it ?

[Lumabots]

should be ready for review

[Lumabots]

just need to specify that this is breaking inside the changelog cos of modification of get_or_fetch and removal of get_or_fetch_user

[Paillat-dev]

This pr should not be breaking, it doens't need to be. Things that aren't needed anymore can be marked as deprecated, and removed later in a bigger release