Revert "Merge core/typing (#432)"

[krittick]

This reverts commit 6e65959.

Summary

Reverts #432 as it's causing errors with slash command registration. e.g.

discord/enums.py", line 646, in from_datatype
    if datatype.__name__ in ["Member", "User"]:
AttributeError: 'Option' object has no attribute '__name__'. Did you mean: '__ne__'?

Further review of the changes in #432 is needed before re-merging.

Checklist

• 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
• 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, ...)