add qemu and virt-viewer

modules/nixos/virtualisation/qemu.nix

@@ -4,12 +4,20 @@
   ...
 }: {
   virtualisation = {
-    libvirtd.enable = true;
+    libvirtd = {
+      enable = true;
+      qemu = {
+        swtpm.enable = true;
+        ovmf.enable = true;
+        ovmf.packages = [pkgs.OVMFFull.fd];
+      };
+    };
   };
 
   users.users.${username}.extraGroups = ["libvirtd"];
 
   environment.systemPackages = with pkgs; [
     virt-manager
+    virt-viewer
   ];
 }