Add dct: metadataPrefix to rights mapping case block.
In looking more closely at some of our errors from the July ingest, we discovered some of them are missing rights data because the dct:accessRights field wasn't mapped to dc:rights. Here is an example:
DPLA can adjust the rights mapping to include both dct and dc as a valid metadata prefixs for mapping. This would pull in the freetext rights values without additional remediation on WI's part.