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，將連結的 Scala LoggingServletTransportProvider 與 Java SDK 目前的 builder 和受保護的 transport 方法進行比較。確定如何透過請求追蹤公開使用者選取的輸出檔案，而不依賴無法存取的建構子或方法。當使用者可以設定檔案，並查看 MCP server 與 client 之間交換的請求資訊時，即視為完成。