[gRPC] Responses logged in a way that cannot be executed by httpYac

[morigs]

When executing gRPC in httpBook it logs the response (cell output) into the .http file the same way as for HTTP requests.

However, gRPC responses start with GRPC, that is the same as GRPC directive in httpYac:

GRPC 0  - OK
content-type: application/grpc

This causes httpYac to interpret them as new gRPC calls and return the following error:

Url 0  - OK does not match pattern <server>/<service>/<method>