Implement mock streaming methods

[grayhemp]

Basically to add code generation for streaming methods here
https://github.com/SafetyCulture/s12-proto/blob/master/protobuf/protoc-gen-gogrpcmock/plugin/plugin.go#L99

[grayhemp]

@rogchap @arkadysafety @codingrhythm please let me know if you guys are working on it already in SafetyCulture, otherwise I'll take it.

[rogchap]

Hey @greyhemp; we do have it as a task “TODO” on our roadmap as we have a number of our APIs using (server) streaming. But it’s yet to be actively worked on right now.

[codingrhythm]

@rogchap nop, I am not working on this one