elmPackages: fix nodejs packages

[turboMaCk]

Fixes regression caused by
4c60ee3da1e3a9c2441ebeb1c755049555624924 (pull: #142915)
following patch of nodePackages using nodejs-14_x
2c3b3e69ad3306fa0711eebdac98e010c7a2d6aa (pull: #149120)

- clenups and updates in generate-node-packages.sh
- specify nodejs version in default.nix

This makes elmPackages.* build with nodejs-14
which resolves the issue with npm installation failing

resolves #152745

cc @jerith666 for review

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 22.05 Release Notes (or backporting 21.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
  • (Release notes changes) Ran nixos/doc/manual/md-to-db.sh to update generated release notes
• Fits CONTRIBUTING.md.

---

Related:

• nodejs: switch from 14.x to 16.x to keep up with the lts release #142915
• nodejs: switch from 14.x to 16.x to keep up with the lts release #142915

[jerith666]

Belatedly, this looks great and fixes the build for me -- thanks!