feat: add tool_name() method to CallToolRequest

[hashemix]

📌 Summary

Added a new handy function to get the tool name from the CallToolRequest object:

Usage Example:

async fn handle_call_tool_request( &self, request: CallToolRequest)->CallToolResult{

       if request.tool_name() == SayHelloTool::tool_name() {
            CallToolResult::text_content( "Hello World!".to_string(), None )
        }

}