feat: allow usage of unicode emoji in PartialEmojiConverter

[Lumabots]

Summary

Currently only custom emoji are supported by the converter, now unicode emoji (and other emoji) are supported.
I implemented a check that rely on #2815 to make sure the emoji is a valid unicode

Information

• 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, 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.