waybar: make the systemd target that pulls in waybar configurable (#399673)

      // lib.mkOption {

        apply = pkg: pkg.override { systemdSupport = true; };

      };

    systemd.target = lib.mkOption {

      type = lib.types.str;

      description = ''

        The systemd target that will automatically start the Waybar service.

      '';

      default = "graphical-session.target";

    };

  };

  config = lib.mkIf cfg.enable {

    environment.systemPackages = [ cfg.package ];

    systemd = {

      packages = [ cfg.package ];

      user.services.waybar.wantedBy = [ "graphical-session.target" ];

      user.services.waybar.wantedBy = [ cfg.systemd.target ];

    };

  };