Create sorted answer options inside the already existing session object "qans_designation_groups"

Currently the preview mode of the question theme creates a new object in session storage. However this object has the generic name "sorted_answer_options". We should create an extra property for each of the groups in the already existing "qans_designation_groups" object such that next to the "members" property, they also have a "sorted_members" property. We check with each question whether this property for the relevant group already exists and otherwise we created it, based of the members property.