Motivation for this change

Updates code-server to 3.8.0.

3.8.0 removes the need to run VSCode patches and fetch submodules, which simplifies the script a bit.

I added support for Darwin, tested on MacOS 10.15.7 -- It required patching the install scripts of a few packages that aren't needed at runtime. I used patch for this rather than sed because it seemed easier to review the changes, but let me know if one or the other is preferred and I can switch it out if necessary.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• 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 nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.