nixos/gdm: generate users to reduce copy&past code

    services.xserver.displayManager.lightdm.enable = false;

    users.users.gdm = {

    users.users = lib.mkMerge [

      {

        gdm = {

          name = "gdm";

          uid = config.ids.uids.gdm;

          group = "gdm";

          description = "GDM user";

        };

    users.users.gdm-greeter = {

        gdm-greeter = {

          isSystemUser = true;

          uid = 60578;

          group = "gdm";

          home = "/run/gdm";

        };

      }

    users.users.gdm-greeter-1 = {

      isSystemUser = true;

      uid = 60579;

      group = "gdm";

      home = "/run/gdm-1";

    };

    users.users.gdm-greeter-2 = {

      isSystemUser = true;

      uid = 60580;

      group = "gdm";

      home = "/run/gdm-2";

    };

    users.users.gdm-greeter-3 = {

      isSystemUser = true;

      uid = 60581;

      group = "gdm";

      home = "/run/gdm-3";

    };

    users.users.gdm-greeter-4 = {

      (lib.genAttrs' [ 1 2 3 4 ] (

        i:

        lib.nameValuePair "gdm-greeter-${toString i}" {

          isSystemUser = true;

      uid = 60582;

          uid = 60578 + i;

          group = "gdm";

      home = "/run/gdm-4";

    };

          home = "/run/gdm-${toString i}";

        }

      ))

    ];

    users.groups.gdm.gid = config.ids.gids.gdm;