fix(voice): Voice internals rewrite to fix things

[DA-344]

Summary

If you don't want your code to explode or something similar, don't use this PR, thanks. ;)

WIP.

A rewrite to its internals to fix various things.

I don't expect this to be merged on 2.7, so it should not block it

This is partially inspired on discord.py's voice code & imayhaveborkedit/voice-recv

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.

Related

Fixes #2833