fix: use networkd for all kubevirt guest

lib/genKubeVirtGuestModule.nix

@@ -4,7 +4,9 @@
   networking,
   ...
 }: let
-  inherit (networking.hostsAddr.${hostName}) iface;
+  inherit (networking) mainGateway nameservers;
+  inherit (networking.hostsAddr.${hostName}) iface ipv4;
+  ipv4WithMask = "${ipv4}/24";
 in {
   # supported file systems, so we can mount any removable disks with these filesystems
   boot.supportedFilesystems = [
@@ -16,11 +18,20 @@ in {
     "exfat"
   ];
 
-  networking = {
+  networking = {inherit hostName;};
-    inherit hostName;
+  networking.useNetworkd = true;
-    inherit (networking) defaultGateway nameservers;
+  systemd.network.enable = true;
-    inherit (networking.hostsInterface.${hostName}) interfaces;
+
-    networkmanager.enable = false;
+  # Add ipv4 address to the bridge.
+  systemd.network.networks."10-${iface}" = {
+    matchConfig.Name = [iface];
+    networkConfig = {
+      Address = [ipv4WithMask];
+      Gateway = mainGateway;
+      DNS = nameservers;
+      IPv6AcceptRA = true;
+    };
+    linkConfig.RequiredForOnline = "routable";
   };
 
   # This value determines the NixOS release from which the default