Support playing arbitrary mod file URL

[runlow]

Expected
Play mods that aren't on Modarchive from URL.

Actual
Only seem to be able to play files from Modarchive.

Why

• Use cases: unfinished track, not added yet to Modarchive, uploaded to another module sharing site, hosted on own site, or only showing some short musical idea that's not meant as a full song.
• Every now and then looking for a player when sharing modules (that aren't on modarchive) with people who don't necessarily know how to play them. If they do just want it to be more convenient. I know that you could render mod files to mp3 but that's not the same, although it's the next best thing.
• Maybe this player could additionally be a player for such modules.

Possible solutions

• Syntax could be: https://coolmodfiles.com/?trackurl=https://example.com/foo.s3m
• CORS would have to accept other domains
• allow data URI for tiny modules
• allow shortened links (via url shorteners)

Extra

• Bassoon tracker seems to load via URL: https://www.stef.be/bassoontracker/?file=http://modland.antarctica.no/pub/modules/Protracker/Radix/crisis%20inverted.mod