Pass allHosts as a special arg to the host configs

modules/system/networking/overlay.nix

@@ -1,7 +1,7 @@
 {
   config,
-  self,
   lib,
+  allHosts,
   ...
 }:
 let
@@ -57,7 +57,7 @@ in
     dnsServers = lib.mkOption {
       type = lib.types.anything;
       default =
-        self.allHosts
+        allHosts
         |> lib.attrValues
         |> lib.filter (host: host.config.custom.services.dns.enable)
         |> lib.map (host: host.config.custom.networking.overlay.address);