Added changes to add nest extractor

[EthanMuir]

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• Searched the bugtracker for similar pull requests
• Read adding new extractor tutorial
• Read youtube-dl coding conventions and adjusted the code to meet them
• Covered the code with tests (note that PRs without tests will be REJECTED)
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[dirkf]

Please

1. revert commit e8eb999 in this branch (maybe review PR [bandlabextractor] added new bandlab extractor for track, album, and playlist… #31206 and offer any good bits from the commit there?)
2. complete the PR template.

[dirkf]

And
3. consider incorporating PR #31274, stalled because the PR author didn't respond to review comments, or closing this in favour of it in case I might have time to finish it myself.