Add a new widget which that provides matching for data product subtype, if the appropriate column is discovered in an ObsCore-like table's columns. Exact or approximate string matching should be implemented. Query against service should be properly generated. Firefly should have a top-level configuration for the sample values for the widget (e.g. explaining the sub_type is a Rubin Butler dataset type.)
Optionally, augment the UI by making the field autocomplete with the available selections and display the number of possible subtypes for a given ObsCore-like table.