feat(virtualisation): set userns auto for containers

virtualisation/containers.nix

@@ -0,0 +1,10 @@
+_:
+
+{
+  # Enable /etc/containers configuration (used by podman, cri-o, etc.)
+  virtualisation.containers.enable = true;
+  virtualisation.containers.containersConf.settings = {
+    # Create unique User Namespace for the container
+    containers.userns = "auto";
+  };
+}