Import sheet heading validation

A sheet with headings valid only for source_identifier, model, visibility, parents, title, and use:ServiceFile passed metadata validation.

* All the other headings have a "-test" suffix but no errors were returned during validation.

* title was initially flagged as invalid when it had the same suffix (StandardError - Missing mapping for at least one required element, missing mappings are: title)

The files associated with this sheet successfully ingested into Comet with little metadata.

Sheet: /comet-ingest/manager-exports-testing-csv/Spectral Refraction Modeling(test heading validation).csv

Importer: https://lib-comet-sandbox.ucsd.edu/importers/84?locale=en

Collection: https://lib-comet-sandbox.ucsd.edu/collections/41880?locale=en