I think we should move the "set track lengths" functionality to the release editor, because:

• The display of the "set track lengths" edit has issues: MBS-1348 and MBS-2948. Moving the functionality to the release editor would make it (part of) an "edit medium" edit instead, solving both problems.
• The current edit type edits multiple releases when it shouldn't (MBS-3936). Moving it to the release editor would mean it only edits one release at a time.
• The current edit causes lot of conflicts if you want to edit the medium and set the track lengths from a disc ID. Moving it to the release editor means you can do both at the same time.
• The release editor prevents you from changing track lengths if there are disc IDs but it's not obvious what you should do instead. Moving it to the release editor would make it easier to find and be more intuitive.
• There are multiple ways to enter edits to change track lengths, which use different edit types which are displayed differently. Moving it to the release editor and using the edit medium edit type would mean we only use one edit type which makes it more consistent.