Ability to generate status codes from user code

[moleike]

As it stands now, we have no way to propagate/generate gRPC statuses from a server application. Whenever the application errors, the server encodes it into an UNKNOWN status. The codes are documented here: https://github.com/grpc/grpc.io/blob/main/content/en/docs/guides/status-codes.md

[Jasper-M]

I think adding a StatusRuntimeException like in grpc-java might make sense. And seems easy to implement as well.

[hamnis]

this sounds reasonable, would you be willing to add a PR for that?

[moleike]

Sure thing, I'll give it a stab soon.