add support of custom youtube_dl implementation

[fmigneault]

Allows to make use of custom but equivalent youtube_dl implementation transparently.

Multiple threads seem to indicate that https://github.com/ytdl-org/youtube-dl is slowly/unofficially deprecated, or at the very least not maintained.

Instead, https://github.com/yt-dlp/yt-dlp can be used directly as its successor. Initializing with BaseYouTubeMusicDL(youtube_downloader=yt_dlp.YoutubeDL) works properly and avoids some long lasting issues about slow download speeds, amongst other things.

Using this approach allows rapid switch to any package that implements the same methods as YoutubeDL, without needing to re-implement all the operations in BaseYouTubeMusicDL._download.

[fmigneault]

Thank you for the integrations.