Fix ResultIterator

Summary:
Previously it had a copy contructor that just assigned the d pointer
of the rhs to the new object, meaning both objects had the same d pointer
and thus we would end up with a double delete when both got deleted.

Now i've made the copy contructor and assignment operator non existing to have this problem

But we need a move constructor since the class is typically used as

Baloo::ResultIterator it = query.exec();

and that stops working if we delete the regular copy and assignment operators

Reviewers: Baloo, bruns, poboiko, apol

Reviewed By: apol

Subscribers: apol, kde-frameworks-devel, Baloo

Tags: Frameworks, Baloo

Differential Revision: https://phabricator.kde.org/D18237