Add Option to Select Different Resolutions to Generate for Web Videos and HLS

[Mike35538]

Describe the problem to be solved

With Web Videos enabled along with HLS, PeerTube always transcodes a video into all the Web Video resolutions automatically. So if the selected resolutions are 1080p, 720p, 480p, 240p, you automatically have a Web Video version and HLS version of each of those resolutions. It seems like users always download the highest resolution file via the Direct Download link. I feel like it is such a rare instance that a user will actually direct download the lower resolution files like 480p or 240p, but these lower resolutions are important for the HLS user experience. I know the instance admin can manually delete off lower resolutions in the video list, but it would be nice to be able to set Web Video output resolutions separate from HLS Output resolutions. Furthermore, keeping the original video file is being implemented in #6157, maybe allow for an option to keep Web Videos of Original file and/or other resolutions. If a user truly wants a lower resolution Web Video copy, then they can download the high resolution video and manually encode it down. Or the instance admin could choose to keep only 1080p and 240p Web Videos, but not all the other HLS resolutions that are enabled.

Describe the solution you would like

If Web Videos and HLS are enabled, have the option to enable different resolutions for each.
For example, you could choose to have:
Web Video output resolutions: Original File, 1080p, 240p
HLS output resolutions: 1080p, 720p, 480p, 240p

This would reduce the file storage load for unnecessary Web Video resolutions, as well as reduce unnecessary transcoding of these resolutions.
Thanks!