Fix CopyAdvisorUtil.copy2 to copy IsRelatedTo-statements left out before

This implementation works so that it copies any IsRelatedTo statements
where both the subject and object have been copied during the normal
(old) copy process. The statements are marked as pending during the copy
and post-processed after everything else has been copied.

gitlab #607

Change-Id: I9170a448c127e0c7de6eae4260db5799ad7644bb
(cherry picked from commit 99395a7780ef1626d3ae97183ef4ae717f32b215)