Add support extended google.api.annotations with response field

[doroginin]

After this changes you can add binding with request/response mapping to repeated fields.

syntax = "proto3";

import "github.com/doroginin/grpc-gateway/third_party/googleapis/google/api/annotations.proto";

service Strings {
    rpc ToUpper (String) returns (String) {
        option (google.api.http) = {
            post: "/strings/to_upper"
            body: "str"
            response_body: "str"
        };
    }
}

message String {
    repeated string str = 1;
}

And in the result your request body will be: ["test","boo"] and response body will be: ["TEST","BOO"]

[mwf]

Need CI fix and a decision about running subtests individually.

[mwf]

Typo - build is used as first target

[mwf]

I don't like this protoc-build in every sub-test - maybe it's better to run them once in the core Makefile.

And if you want to run a single test individually - just prepare your environment manually running make protoc-build and then run make test.

[mwf]

or we could do even better and make 2 targets.
test would explicitly run protoc-build - you would use it in manuall run
test-ci won't call protoc-build - it would be used in the core Makefile to run all tests.

[doroginin]

discussed verbally

[mwf]

Hmm, then the swagger would break if clay consumers won't use github.com/utrack/grpc-gateway explicitly.
Maybe it's better to keep it as it is.

[doroginin]

Now also supported repeated field in GET
See: integration/binding_with_body_and_response/pb/strings.proto
GET request like this: /strings/to_upper/v2?str=test&str=boo