Makes it possible to fix https://github.com/jmbannon/ytdl-sub/issues/756
In the case that uploader_url does not equal the input url, keep trying to fetch uploader_url to get all possible metadata that yt-dlp does not provide in a single API call
Partial fix to https://github.com/jmbannon/ytdl-sub/issues/853
Makes computing sibling metadata optional, defaulted to False. This prevents excessive memory usage when scraping large channels
A complete gutting of the internals of ytdl-sub to support functions in our variable syntax, in addition to being able to access a yt-dlp entry's .info.json fields using functions. Functionally, ytdl-sub should still look and behave the same from a user-perspective.
With so many lines of code changed (+8927, -2708), no doubt there will be new issues. Please make a GH issue or reach out on Discord if your config/subscriptions break in any way/shape/form.
Details on how to use function support will come soon in the form of proper documentation in our readthedocs.
