desktop: Use vagrant with libvirtd

Sometimes it's necessary to spin up a virtual machine.

NixOS conveniently has libvirt support built-in, so virtualbox
isn't necessary.

hosts/phone/configuration.nix

@@ -199,7 +199,7 @@ in
   documentation.man.generateCaches = false;
 
   hardware.graphics.enable32Bit = mkForce false;
-  virtualisation.virtualbox.host.enable = mkForce false;
+  virtualisation.libvirtd.enable = mkForce false;
 
   powerManagement = {
     enable = true;

modules/desktop.nix

@@ -78,6 +78,11 @@ in
       };
     };
 
+    virtualisation.libvirtd = {
+      enable = true;
+      onBoot = "ignore";
+    };
+
     services = {
       udisks2 = {
         enable = true;
@@ -141,6 +146,7 @@ in
           ringracers
           jamesdsp
           texliveFull
+          vagrant
           ;
 
         inherit (nix-config.inputs.sakaya.packages.${pkgs.system}) sakaya;
@@ -158,6 +164,10 @@ in
       })
     ];
 
+    nixpkgs.config.allowUnfreePredicate = pkg: builtins.elem (lib.getName pkg) [
+      "vagrant"
+    ];
+
     fonts = {
       enableDefaultPackages = false;