feature: build a script/tool output that doesn't rely on nix being installed

[jpetrucciani]

inspired by this reddit comment

it would be interesting to perhaps have an additional output in the derivation that is the script with references to the nix store removed. Also, maybe a comment at the top of the file as well listing required deps?

this way, you could take the script and just copy/share it, but you'd have to depend on the users you distribute to having those dependencies already installed. Perhaps we could also check for them at the top of the generated script?