API - Add a method that returns only a list of items listed for sale

This will reduce the load on the server, since the request https://cs2.market/api/v2/items?key= returns not only those items but also all items currently locked for trading (trade lock), and there can be a lot of them, which unnecessarily burdens the server. Alternatively, you can add a parameter to the request https://cs2.market/api/v2/items?key= that allows you to specify which items with which statuses you want to receive in the response. I don’t really need this myself, but these unoptimized requests might put an unnecessary strain on the server.