[FEATURE] Adopt protoc-gen-jsonschema protomessage options and generate a jsonschema from a proto message

[ghstahl]

protoc-gen-jsonschema

I would like to define my jsonschema in a proto file vs a golang struct.

Lets assume OptionRequiredField is a golang struct generated from example proto.
i.e.

jsonschema.Reflect(&OptionRequiredField {})