Get Field Options v1.2

Retrieve the possible values for one or more dataset fields, for use as filter values in dataset queries. Pass the field names you want options for in the fields array. The response is an object keyed by field name, where each value is an array of {id, value} objects. Use the id values as filter values when querying dataset endpoints. Optionally supply filters to scope the returned options. V1.2 endpoint: 400 and 403 error responses use RFC 7807 application/problem+json. Note: unrecognised field names may result in a 500 response with a plain-text body rather than a structured error payload.