Add client side streaming support

[Cidan]

Client side streaming support, in particular when used with bidirectional RPC's, allow for a significant reduction in boilerplate for interactive systems, i.e. a chat server.

Are there plans to add client side streaming at any point?

Thanks!

[lyonlai]

my understanding is that there's no plan for grpc-gateway to support client side streaming (see link below). We currently have no plan unless this situation changes.

https://github.com/grpc-ecosystem/grpc-gateway#no-plan-to-support