[providers] Fix issue when loading cardinality information for relations

The cardinality information is read from a cardinality string, e.g. "?*". There are two methods, getFromCardinality and getToCardinality to read the cardinality for the subject and range/target, respectively, of the relation. However the two methods were the same, both reading the first character.

In cardinality strings the first character correspond to the range/target of the relation and the second to the subject/origin. Therefore, this changeset fixes the getFromCardinality method to read its data from the second character of the cardinality string.