Add support for seeing COG children from the childCog subview

[grantfitzsimmons]

It is clear that it is cumbersome to not enable users to see the children of nested COGs from the parent COG form.

You can see that there is a COG child, but there is no indication of how many children. You cannot add a subview or button as it is forbidden or ignored in the XML when I have tried.

Screen.Recording.2024-12-03.at.4.37.30.PM.mov

It would be nice to have a button or subview for the childCog.children that could be added to the collectionobjectgroupjoin form.