Adding code showing how to add Child items

[omascia]

It would be really useful to add some more functionnality to CppCustomVisualizer, to bootstrap adding custom child views. Maybe two of them.

Very simply, the two custom child items could be "Date" and "Time". Both are combined into the root item visualisation, but could be made available as custom children for the purpose of demoing the right way to do it.

That would add great value to this excellent sample.