Instead of relying on the official Google YouTube API (limited, subject
to breaking changes with short/no notice depending on Google's strategy
against scrapers, and with an initial setup that has a high cost), we'll
just stick to Piped from now on.
It's free, it doesn't require API keys, it's unlikely to change, it's
not subject to Google's hostile practices against developers, and
anybody can run an instance.
`youtube-dl` is mostly dead and there are several forks available, thus
we need to give the user the ability to pick which `youtube-dl`
executable fork they want to use.
Among these, `yt-dlp` is probably the most maintained today and it's
also included in many default repos, so it's been added as an extra
requirement for all the media plugins.
Closes: #268