Motivation for this change

The previous zip command wasn't including directories. This Sublime package only has one directory in it, so the resulting bug was subtle. The directory contained the send2trash Python package, so the result was that file deletion didn't work.

This diff also includes a few minor shufflings-around to make the Nix package slightly easier to debug.

Things done

• Tested using sandboxing
  (nix.useSandbox on NixOS,
  or option build-use-sandbox in nix.conf
  on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • Linux
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.