test-vm: Add alias of shutting down the VM

hosts/test-vm/configuration.nix

@@ -31,6 +31,10 @@
       };
     };
 
+    environment.interactiveShellInit = ''
+      alias sd='sudo shutdown now'
+    '';
+
     environment.systemPackages = [ ];
 
     system.stateVersion = "24.05";