feat: add on_raw_member_update event

[Soheab]

Summary

This PR adds a new event called on_raw_member_update. This event is dispatched regardless of whether the member is cached. Handy for bots with chunking disabled and other reasons.

Fixes #3001

Information

• [x] 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.
  • [x] I have updated the documentation to reflect the changes.
• [x] If type: ignore comments were used, a comment is also left explaining why.
• [x] I have updated the changelog to include these changes.

[pycord-app[bot]]

Thanks for opening this pull request! Please make sure you have read the Contributing Guidelines and Code of Conduct.

This pull request can be checked-out with:

git fetch origin pull/3012/head:pr-3012
git checkout pr-3012

This pull request can be installed with:

pip install git+https://github.com/Pycord-Development/pycord@refs/pull/3012/head