[ATSPI] make ScrollToChild use descendant

It is not make a child visible if the child is 1st generation child.
Usually the 1st generation child is content container.
So we need to use descendant.

This patch makes the CollectionView work with following change;
https://github.com/Samsung/TizenFX/pull/3726

We need to enhance this part and related places later.

Change-Id: I9e88312b7b1936909dc350cc1154f2a18e900748