nixos/automatic-timezoned: set `time.timeZone` to `null` to avoid silent overriding (#347217)

- ZFS now imports its pools in `postResumeCommands` rather than `postDeviceCommands`. If you had `postDeviceCommands` scripts that depended on ZFS pools being imported, those now need to be in `postResumeCommands`.

- `services.automatic-timezoned.enable = true` will now set `time.timeZone = null`.

  This is to avoid silently shadowing a user's explicitly defined timezone without recognition on the user's part.

- `services.localtimed.enable = true` will now set `time.timeZone = null`.

  This is to avoid silently shadowing a user's explicitly defined timezone without recognition on the user's part.

          timezone up-to-date based on the current location. It uses geoclue2 to

          determine the current location and systemd-timedated to actually set

          the timezone.

          To avoid silent overriding by the service, if you have explicitly set a

          timezone, either remove it or ensure that it is set with a lower priority

          than the default value using `lib.mkDefault` or `lib.mkOverride`. This is

          to make the choice deliberate. An error will be presented otherwise.

        '';

      };

      package = mkPackageOption pkgs "automatic-timezoned" { };

  };

  config = mkIf cfg.enable {

    # This will give users an error if they have set an explicit time

    # zone, rather than having the service silently override it.

    time.timeZone = null;

    security.polkit.extraConfig = ''

      polkit.addRule(function(action, subject) {

        if (action.id == "org.freedesktop.timedate1.set-timezone"