[StreamableHTTPServerTransport] Support passing auth context downstream into tool/prompt handlers

[its-nikhil]

Pretty much duplicate of #171

Passing down auth context in tools/prompt/resources handlers would also be required in StreamableHTTPServerTransport

typescript-sdk/src/server/streamableHttp.ts

Line 115 in 1317767

onmessage?: (message: JSONRPCMessage) => void;