Support loggging grpc status details

[devnev]

Problem

GRPC status messages on the wire are protos and include a field called details that allows further protos to be attached to the results - see https://github.com/grpc/grpc/blob/master/src/proto/grpc/status/status.proto#L91

Example of such an additions are in the error_details.proto file https://github.com/googleapis/googleapis/blob/master/google/rpc/error_details.proto

In particular, ErrorInfo can have extended error details and metadata that would be helpful to log

In v1, these could be extracted and added to the fields using the custom message producer option

Suggestion

Probably not a custom message producer like v1, but some kind of option to extend fields with error details or more generally with post-call fields

[johanbrandhorst]

Hi, thanks for your issue! I'm a little confused exactly what the proposal is here - are we talking about a new option, or some sort of automatic behaviour? Could you share an example of the API you'd like to see, what it would do, and alternatives you've considered? Thanks!