nixos/modemmanager: fix missing awk and xxd in FCC unlock script PATH

The FCC unlock scripts use a few helpers not automatically included with
systemd, which we need to set up the service path for. Two of the scripts
that come from upstream use awk and xxd, which were missing in the list.
That made the script mistakenly yield an empty response, which ultimately
makes the unlock fail.

As of today, this fix covers the MediaTek T700, sold e.g. with the
ThinkPad X1 Yoga Gen 8 as Fibocom FM350-GL.

nixos/modules/services/networking/modemmanager.nix

@@ -64,10 +64,15 @@ in
 
     systemd.services.ModemManager = {
       aliases = [ "dbus-org.freedesktop.ModemManager1.service" ];
-      path = lib.optionals (cfg.fccUnlockScripts != [ ]) [
-        pkgs.libqmi
-        pkgs.libmbim
-      ];
+      path = lib.optionals (cfg.fccUnlockScripts != [ ]) (
+        with pkgs;
+        [
+          gawk
+          libmbim
+          libqmi
+          xxd
+        ]
+      );
     };
 
     /*