Cut the voice recording from pycord and insert it into discord.py-self

[markmelix]

Summary

I've just had a problem when I had to record guild member's voice using my account as a self-bot (as I have no rights to just throw usual bot to the server). Thus, the only python library providing Discord API wrapping with self-bot support I can use is discord.py-self. As discord.py-self doesn't have fine voice recording support, I tried cutting py-cord's one and just inserting it directly into the discord.py-self code. I did some voice recording tests using my own self-bot and it works great. There were only changes to the voice related parts, so nothing breaks when I run usual bot. I decided to make a PR, maybe my changes would be useful.

General Info

• [x] If code changes were made then they have been tested.
  • [ ] I have updated the documentation to reflect the changes.
• [ ] This PR fixes an issue (please put issue # in summary).
• [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, ...)

[dolfies]

Thank you for the PR, but pycord's implementation has numerous issues and isn't something I want to include in this state.

However, there's an upstream PR that adds support for receiving audio. If/when that gets merged, I'll be happy to pull that in.