use subcommands in plugin updaters

[teto]

• update.py: introduce subparsers for plugin updaters
• doc/updaters: update command to update editor plugins

Description of changes

This is preliminary work to help create more powerful plugin updaters.
Namely I would like to be able to "just add" plugins without refreshing
the older ones (helpful when github temporarily removes a user from
github due to automated bot detection).

Also concerning the lua updater, we pin some of the dependencies, and I
would like to be able to unpin the package without editing the csv
(coming in later PRs).

Things done

• 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/)
• 23.05 Release Notes (or backporting 22.11 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
• Fits CONTRIBUTING.md.

[figsoda]

--github-token doesn't seem to work anymore, at least for the vim update script

[teto]

@figsoda this should be fixed. To sum up, the only effective change right now is instead do doing update.py --add XXX is that you should now run update.py add. The endgame is more ambitious but let's break stuff after the nixos release and not right before. Also I can't help but feel like we are recreating some abstraction over lockfiles. I feel like we should do it differently (more integration with nix-update or flakes or I dunno) but this should be adressed later.

[figsoda]

thanks, I will test it out in a bit