Get the IDs of all assets in the exchange in reverse block height of creation order.
Request:requestType is getAssetIdsfirstIndex is the zero-based index to the first asset ID to retrieve (optional)
lastIndex is the zero-based index to the last asset ID to retrieve (optional)
Response:
(A) assets is the array of asset IDs
(N) requestProcessingTime is the API request processing time (in millisec)