feat: Automatically mount /persist/dots in VM

hosts/nixos-testbed/configuration.nix

@@ -53,6 +53,13 @@
     };
   };
 
+  # VM-specific. }:3
+  fileSystems."/persist/dots" = {
+    device = "mount-dots";
+    fsType = "virtiofs";
+    mountPoint = "/persist/dots";
+  };
+
   # HACK: This is here temporarily so I can use `/persist` without
   # Impermanence.  This can be removed once impermanence is enabled.
   # Create a group called `cfg.persistGroupName`