Add GDM option to hide users list

[8573]

Issue description

I'd like to have a NixOS option to make GNOME Display Manager (GDM) hide the list of users that it shows on its log-in screen. This sounds simple enough (1, 2), and I wrote a patch, but I don't understand DConf or know what I'm doing with this GNOME stuff, nor do I know how to test a patch to a NixOS module.

Technical details

• system: "x86_64-linux"
• host os: Linux 5.10.62-hardened1, NixOS, 21.11 (Porcupine)
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.3.15
• channels(root): "nixos-21.11pre313614.09cd65b33c5"
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos

[Artturin]

https://nixos.wiki/wiki/Nixpkgs/Reviewing_changes

[stale]

I marked this as stale due to inactivity. → More info