[#112545867] Correct relinking of collections when a new collection is inserted in the middle.
[#112545867] Correct relinking of collections when a new collection is inserted in the middle.

We were pushing the child collection to the parent's 'children' array.
There is no reason why we shouldn't be setting the zero'th element.

concord-consortium/codap,concord-consortium/codap,concord-consortium/codap,concord-consortium/codap,concord-consortium/codap