The value for a relationship can be a scalar object (1:1), a collection (1:n), a map (1:n, but with dynamic
relationship types) or a map (1:n) with properties for each relationship. This method unifies the type into
something iterable, depending on the given inverse type.
rawValue - The raw value to unify
A unified collection (Either a collection of Map.Entry for dynamic and relationships with properties or a
list of related values)