This property controls whether a footer will be added to the list view.
The default value is false.
When this property is set to true, Unity adds a footer under the scroll view.
This footer contains two buttons:
A "+" button. When clicked, it adds a single item at the end of the list view.
A "-" button. When clicked, it removes all selected items, or the last item if none are selected.
If the makeFooter callback is set, it will override this property.