Fix EnforceReadonlyAttributes to support using a class's custom getter/setter methods for readonly attributes.
Add API endpoint to get flattened list of fields in a dataset.
Add API for applying labels to dataset fields.
Add UI for applying labels to dataset fields.
Include field types in flattened field list.
Break field selection for filter out into separate widget. Divide field list by common flag and show field label if it has one.
If only fields in common/other group are present, don't show groups.