Renamed field-options

I've secured an extention to our options range, which means that we can use it for things other than just FieldOptions (MessageOptions, FileOptions, EnumOptions etc). These will be used to offer fine-grained control over the schema generated behaviour.

    string hidden1  = 3 [(protoc.gen.jsonschema.field_options).ignore = true];

  string query = 1 [(protoc.gen.jsonschema.field_options).required = true];