Summary:
Ensure that `lookupOne` (via `RecordSet.get_one`) pays attention to the `sort_by` parameter by picking the first of its sorted list of row IDs.
Allow specifying reverse sort order in `sort_by` by adding `"-"` before the column ID.
Suggested in https://grist.slack.com/archives/C0234CPPXPA/p1665756041063079
Test Plan: Extended Python lookup test
Reviewers: jarek
Reviewed By: jarek
Differential Revision: https://phab.getgrist.com/D3675