Support using the same port for Spring WebFlux and gRPC

[making]

Similar to #18, but it would also be desirable to be able to share the Netty for Spring WebFlux with the Netty for gRPC like Armeria
https://armeria.dev/docs/advanced-spring-webflux-integration

[linux-china]

How about reactive-grpc for Reactor style? I create a demo on https://github.com/linux-china/grpc-reactive-server

[dsyer]

If anyone wanted to look at this, there is a Protbuf{Encoder,Decoder} pair (and an associated message writer) in spring-web. It doesn't handle gRPC, but the extension points are there - you just need to take care of the delimiters between messages, and the trailer headers. There is also potentially an issue with bidirectional streaming (but it might just work as long as the spring-web components do). the first stage of wupporting webflux would be adding those encoders and decoders. Then we could look at exposing gRPC Bindables as webflux endpoints using functional mappings. Prototype here: https://github.com/scratches/grpc-reflect/tree/main/lib/src/main/java/org/springframework/grpc/webflux