* Handle google.protobuf.Value

gRPC transcoding handles google.protobuf.Value as a catch all value.

* Handle repeated Value + descriptions

* Fix response content

Responses now include schema for Struct and Value types

Found and suggested by @hojongs

* protoc-gen-jsonschema: Share type and format values

* protoc-gen-jsonschema: Handle google.protobuf.Value

+ add protobuf type tests from protoc-gen-openapi

* protoc-gen-openapi: fix info URL

* Fix info URL in tests as well

google.api.HttpBody is another special case, that is handled explicitly by Envoy.

The behavior has been tested with Envoy.

GET requests with google.api.HttpBody as request param, will actually read POST data and pass it along.
This can not allowed in OpenAPI though.

In OpenAPI, the response is defined as Content Type */*.

* protoc-gen-openapi: Expose configuration for enum serialization type
* protoc-gen-jsonschema: Expose configuration for enum serialization type

* Support  with description in OpenAPI V3 proto
* Fix proto generation