feat: message forwarding

[NeloBlivion]

Summary

Implements message forwarding, alongside some small cleanups for other message features.

Information

• [ ] This PR fixes an issue.
• [x] 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, typehinting, examples, ...).

Checklist

• [ ] I have searched the open pull requests for duplicates.
• [ ] If code changes were made then they have been tested.
  • [x] 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.

[NeloBlivion]

more or less done, just need to add mention/role mention handling and partialmessage support... but still 403ing on my bot 😔

[Lulalaby]

unlucky bcs its 95% out. you're in th holdout group. try making a new bot

[Dorukyum]

@NeloBlivion status?

[NeloBlivion]

ah yeah, forgot to tick that box; as far as i've tested there haven't been any issues.

[NeloBlivion]

As far as I've tested it operates fine, would appreciate others testing if they may know of any edge cases/weird behaviour with the attributes of ForwardedMessage but otherwise it's feature complete.

[NeloBlivion]

(Actually haven't done a full review of docs so maybe that'd be a good idea)

[Paillat-dev]

This pr should be marked as fixing

• #2586

[Lulalaby]

done but i still won't pay you

[NeloBlivion]

pls merge this idk

[Lulalaby]

anything for u @NeloBlivion <3