Add an ability to trace requests

Expected Behavior

User can specify a file to dump information about all requests being sent between MCP server and the client

Current Behavior

I don't think there is a way to do it currently.

Context

We created a LoggingServletTransportProvider which does that, but with the new changes that no longer compiles since there is no public constructor. Using the builder and then composing is also not possible because the methods are protected.

We could upstream the LoggingServletTransportProvider or something along these lines if it makes sense.

This is very useful for debugging potential issues with MCP servers especially when users turn on automatic accept.

首先，将链接的 Scala LoggingServletTransportProvider 与 Java SDK 当前的 builder 和受保护的 transport 方法进行比较。确定如何通过请求跟踪公开用户选择的输出文件，而不依赖无法访问的构造函数或方法。当用户可以配置文件并查看 MCP server 与 client 之间交换的请求信息时，即视为完成。