feat: Add Kubernetes examples and update dependencies

- Add Kubernetes examples demonstrating deployment of various
  applications (PostgreSQL, Redis, generic). This improves the
  documentation and provides practical usage examples.
- Add `tokio` dependency for async examples. This enables the use
  of asynchronous operations in the examples.
- Add `once_cell` dependency for improved resource management in
  Kubernetes module. This allows efficient management of
  singletons and other resources.

kubernetes/tests/rhai/crud_operations.rhai

@@ -68,7 +68,7 @@ try {
         "app": "rhai-app",
         "tier": "frontend"
     };
-    let deployment_name = test_km.create_deployment("rhai-deployment", "nginx:alpine", 2, deployment_labels);
+    let deployment_name = test_km.create_deployment("rhai-deployment", "nginx:alpine", 2, deployment_labels, #{});
     print("✓ Created Deployment: " + deployment_name);
     
 } catch(e) {