Prefer "original song" entries when searching for original versions on song submit/edit pages

[Shiroizu]

When adding/editing derivate works, searching for the original version should prefer showing "original song" -entries first.

For example, here the original version is shown on bottom of the search results (should be among the first results).

[ycanardeau]

Available on the beta site, but does it make sense to prefer original song entries everywhere? I wonder if there is some performance penalty. Should we add an option like preferOriginal to the song API?

[CatgirlFrostmoon]

I think ranking the songs by popularity would help a lot, too -- I always run into issues adding covers of Kanaria's works because of the one-word titles, and sorting the songs by popularity would help a lot.