There is CreateCallAndUnwrapIteratorScript() which can traverse
iterator for nodes with sessions disabled. For other nodes this may
still be beneficial: if there is a small number of items, we might read
(or prefetch) all of them in one request. However, this script continues
to work even for large collections, returning both accumulated array and
remaining iterator.
Signed-off-by: Evgenii Stratonikov <fyfyrchik@runbox.com>