[modules] fix microvm.host 'leak'

including the malobeo module caused microvm to include microvm.host
which caused super annoying trouble and 2 days of debugging because
microvm.host.enable defaults to true...

machines/configuration.nix

@@ -137,7 +137,7 @@ in
     specialArgs.inputs = inputs;
     specialArgs.self = self;
     modules = makeMicroVM "vpn" "10.0.0.10" "D0:E5:CA:F0:D7:E6" [
-      self.nixosModules.malobeo
+      self.nixosModules.malobeo.vpn
       ./vpn/configuration.nix
     ];
   };

outputs.nix

@@ -112,12 +112,15 @@ in (utils.lib.eachSystem (builtins.filter filter_system utils.lib.defaultSystems
       self = self;
     });
 
-    nixosModules.malobeo.imports = [
+    nixosModules.malobeo = {
+      imports = [
         ./machines/durruti/host_config.nix
-      ./machines/modules/malobeo/microvm_host.nix
-      ./machines/modules/malobeo/wireguard.nix
       ];
 
+      microvm.imports = [ ./machines/modules/malobeo/microvm_host.nix ];
+      vpn.imports = [ ./machines/modules/malobeo/wireguard.nix ];
+    };
+
     hydraJobs = nixpkgs.lib.mapAttrs (_: nixpkgs.lib.hydraJob) (
       let
         getBuildEntry = name: nixosSystem: