This is in nixpkgs-unstable and PR'ed for 21.05 (#134496) but doesn't
make progress so far, thus init here. Expression is basically copied
from nixpkgs-unstable.
This is basically copied from nixpkgs-unstable's navidrome derivation
but updated to current version.
I'd prefer building this from source, but currently only manage to build
the backend-only version without the web UI, as building both requires
somehow building a node.js package inside a Go package.