Motivation for this change

Needed by vimPlugins.coc-prettier (see discussion here and here).

Fuller context

Coc is a plugin that integrates Intellisense and other async language engines with Neovim/Vim 8 to provide type checking, formatting and other similar capabilities for Vim.

Coc has a modular structure and depends on installing extensions for different languages. Normally, these are installed using :CocInstall within Vim, but there has been an effort to Nix-ify the process by moving the extensions into Nixpkgs: vimPlugins.coc-go, vimPlugins.coc-prettier, etc.

(Many? All?) Coc extensions are essentially NPM packages. Many of the ones that are currently in vimPlugins are broken because they exposing raw source code rather than a properly built NPM package (i.e., one that's had npm run build executed). Hence, we need to do two things to fix them:

1. Add the underlying NPM packages to nodePackages, then
2. Re-export the resulting package within vimPlugins using buildVimPluginFrom2Nix with the package output as the source.

This PR addresses the first step for one extension, coc-prettier. A subsequent PR will fix the plugin on the Vim side using an override. This PR has been closed in favor of #72506, which combines steps 1 and 2 above.

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 nix-review --run "nix-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.

Notify maintainers

cc @adisbladis @rvolosatovs