Multiple designation choices in personalized upload links

For school administrators using GiveCampus Outreach. Controls can differ between the classic email editor and the newer Composer editor.

The legacy simple autofill export has a single designation field, but the school personalization upload supports numbered designation_backend1 through designation_backend4 and corresponding designation_amount columns. Use that supported personalization workflow/current template with stable external_id values, confirm the people and funds exist on the target form, and test each generated recipient link. Do not add arbitrary columns to the simpler autofill uploader assuming it has the same schema.