List custom field offices

A custom_field_office restricts a custom field's visibility to a single office, so the field only appears on jobs, openings, or offers whose office matches. A custom field with no rows in this list is visible to every office — the right default for remote-first or single-office orgs that don't scope fields by location. Filter by custom_field_ids to see which offices a given field is scoped to, or by office_ids to see which fields are scoped to a given office. Office scoping composes with /v3/custom_field_departments: a field carrying both kinds of rows is only visible where both an office and department match.