feat: app emojis

[NeloBlivion]

Summary

Implements discord/discord-api-docs#7010 Very rough draft, considering new emoji classes

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

• [x] I have searched the open pull requests for duplicates.
• [x] 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.

[NeloBlivion]

Removed draft status as this is completely functional, just have to go through and replace instances of Emoji with GuildEmoji (Emoji is still aliased, possibly deprecate for 2.7?)

[Lulalaby]

@NeloBlivion can u finish this (see comment)