feat: Add roots change notification support to MCP server

- Implement roots change notification handler in McpAsyncServer
- Add rootsChangeConsumer builder methods to support single and multiple consumers
- Rename info() builder method to serverInfo() for clarity
- Add comprehensive tests for roots change notification functionality
- Add default server info implementation in Builder

Resolves #39

spring-ai-mcp-sample/src/main/java/org/springframework/ai/mcp/sample/server/McpServerConfig.java

@@ -67,7 +67,7 @@ public class McpServerConfig {
 
 		// Create the server with both tool and resource capabilities
 		var server = McpServer.using(transport)
-			.info("MCP Demo Server", "1.0.0")
+			.serverInfo("MCP Demo Server", "1.0.0")
 			.capabilities(capabilities)
 			.resources(systemInfoResourceRegistration())
 			.prompts(greetingPromptRegistration())