Enable key-sharing and virt-viewer for all VMs

lib/system.nix

@@ -20,6 +20,19 @@
                                     ./config/custom-build-vm.nix
                                 ];
 
+                                virtualisation =
+                                    let
+                                        vmConfig = {
+                                            virtualisation = {
+                                                sharedHostKeys = true;
+                                                virt-viewer = true;
+                                            };
+                                        };
+                                    in {
+                                        vmVariant = vmConfig;
+                                        vmVariantWithBootLoader = vmConfig;
+                                    };
+
                                 # Networking
                                 networking.hostName = name;
                             })