INVENTORY ASYNC RESULT MANAGEMENT
Asynchronous inventory queries always output a result handle which can be used with
GetResultStatus, GetResultItems, etc. A SteamInventoryResultReady_t callback will
be triggered when the asynchronous result becomes ready (or fails).
Find out the status of an asynchronous inventory result handle. Possible values:
k_EResultPending - still in progress
k_EResultOK - done, result ready
k_EResultExpired - done, result ready, maybe out of date (see DeserializeResult)
k_EResultInvalidParam - ERROR: invalid API call parameters
k_EResultServiceUnavailable - ERROR: service temporarily down, you may retry later
k_EResultLimitExceeded - ERROR: operation would exceed per-user inventory limits
k_EResultFail - ERROR: unknown / generic error
