INVENTORY ASYNC MODIFICATION
GenerateItems() creates one or more items and then generates a SteamInventoryCallback_t
notification with a matching nCallbackContext parameter. This API is insecure, and could
be abused by hacked clients. This call is normally disabled unless you explicitly enable
"Development mode" on the Inventory Service section of the Steamworks website.
You should not enable this mode for a shipping game!
Note that Steam accounts that belong to the publisher group for your game are granted
an exception - as a developer, you may use this to generate and test items in your game.
If punArrayQuantity is not NULL, it should be the same length as pArrayItems and should
describe the quantity of each item to generate.