Add duplicate title, subject, and description fields for text in multiple languages

Having fields like title and description offer alternative language versions would also be helpful for discovery.

From Julian: from what I can tell so far, DataCite 3.1 schema lets you specify the language of Title, Subject and Description with a long attribute (4.1 adds the xml lang attribute to Rights) - https://schema.datacite.org/meta/kernel-4.1/doc/DataCite-MetadataKernel_v4.1.pdf. The schema says it accepts only IETF BCP 47 and ISO 639-1 language codes. But I don't think Dataverse knows the ISO language codes for the languages it displays in the Citation block (I vaguely remember a comment about this in a github issue or maybe a Google Group post but can't find it). The Consorcio Madroño Dataverse does this with the DataCite metadata they publish for each dataset: https://edatos.consorciomadrono.es/api/datasets/export?exporter=oai_datacite&persistentId=doi%3A10.21950/O53TLR

And most or all of the DDI elements that Dataverse uses can include a lang attribute (http://www.ddialliance.org/Specification/DDI-Codebook/2.5/XMLSchema/field_level_documentation_files/schemas/xml_xsd/attributes/lang.html). Looks like it accepts any value for now.

see related ticket https://github.com/IQSS/dataverse/issues/4632 for adding record language qualifier

Start by reviewing related issue #4632 and the linked DataCite 4.1 and DDI language specifications. Trace the metadata export endpoint and determine how Title, Subject, and Description are represented today. Done should include an agreed design for language-qualified alternatives and its DataCite/DDI export behavior.