GF-60073: Focus lost after remove all items while focus is on one of the items from moon.DataGridList and moon.DataList

This fix is doing little bit of focus handling on DataList and
DataGridList.

When focused item in the end of the list is removed, focus is moved into
the list. If not, focus is not moving.

DCO-1.1-Signed-Off-By: Kunmyon Choi <kunmyon.choi@lge.com>
GF-60073: Move modelsRemoved spotlight logic to moon.DataListSpotlightSupport mixin.  Add same treatment for modelsAdded, for similar reasons.
DCO-1.1-Signed-Off-By: Kevin Schaaf <kevin.schaaf@lge.com>
Merge pull request #1100 from enyojs/GF-60073-kunmyonchoi

GF-60073: Focus lost after remove all items while focus is on one of the...