Add support for protobuf inputs

[mfateev]

Add support for protobuf inputs

[mfateev]

We should support loading a message from a binary file and specifying the encoding through the command line. This would support any future message format.

[jeffschoner-stripe]

To clarify, the serialization is still JSON but serialized from a proto generated object. It's encoded as json/protobuf for use with the ProtobufJsonPayloadConverter, but tctl sends JSON with the json/plain encoding, which routes to the JacksonJsonPayloadConverter. I believe this could be fixed by providing an option in tctl for setting the json-proto encoding, as opposed to fully serializing to proto binary (encoded as binary/protobuf and handled by ProtobufPayloadConverter).

[mfateev]

I see. Assuming that JSON that is passed to the argument is valid for the protobuf to deserialize it could work.