Unimplemented methods in Smithsonian metadata transformer

[dannymandel]

The following methods are currently unimplemented in Smithsonian and need further definition:

    def sample_registrant(self) -> typing.AnyStr:
        return Transformer.NOT_PROVIDED

    def sample_sampling_purpose(self) -> typing.AnyStr:
        return Transformer.NOT_PROVIDED

    def produced_by_id_string(self) -> typing.AnyStr:
        return Transformer.NOT_PROVIDED

    def produced_by_label(self) -> typing.AnyStr:
        return Transformer.NOT_PROVIDED

    def produced_by_feature_of_interest(self) -> typing.AnyStr:
        return Transformer.NOT_PROVIDED

Once we have documentation on how to implement, please assign back to me for implementation. If we decide that these fields aren't relevant, that is good to know, too, as I'll add comments to the code that indicates this.