List Goldin's search filter enums

Goldin's full filter-enum surface for goldin-search, scoped to one lot pool -- category, sub_category, certification, item_type, and the live auction list (each with its own id, name, and current lot count), plus the sort enum valid for that pool. category/sub_category/certification/item_type are read live from Goldin's own current inventory, not a fixed taxonomy, so results can shift over time. The Auction pool (default) and the Fixed Price "Private Sales" marketplace are disjoint item pools with different certification/item_type values and different sort enums -- pass the same auction_type here and to goldin-search.