* ext: in setting editor

This is more explicit and correctly handles some edge cases

Avoid updateTreeScrollSync when TOC doesn't have the same elements as the settings tree.
And ensure that group counts are always up to date when refreshing the TOC

Fix #66796 - previously there was weird listener behavior described in that issue but it has disappeared

In `Action.run` methods, we don't need an explicit null return value but can use undefined instead

part of strict null work

* ObjectTree/List: Add ariaRootRole option.  Addresses: #65939

* Address @joaomoreno tweaks