feat: Implement LLM configuration validation in create and update routes

- Added `validate_llm_config` function to `llm_service.py` for validating LLM configurations via test API calls.
- Integrated validation in `create_llm_config` and `update_llm_config` routes in `llm_config_routes.py`, raising HTTP exceptions for invalid configurations.
- Enhanced error handling to provide detailed feedback on configuration issues.

surfsense_web/components/sidebar/app-sidebar.tsx

@@ -77,10 +77,10 @@ const defaultData = {
 					title: "Upload Documents",
 					url: "#",
 				},
-				{
-				  title: "Add Webpages",
-				  url: "#",
-				},
+				// {
+				//   title: "Add Webpages",
+				//   url: "#",
+				// },
 				{
 					title: "Manage Documents",
 					url: "#",