ServeHttpHandler support multiple http responses #332
Description
Right now the ServeHttpHandler definition only has one parameter ServeRequest, and the response is specified by the return value of your ServeHttpHandler (or lack thereof). This is limiting in cases where multiple responses may be necessary, such as HTTP 103 Early Hints.
One solution is adding a second parameter ServeReply to ServeHttpHandler which mimics Fastify's Reply construct. This solves the problem in a robust and expandable way.