Bhv 15492 derekanderson

Issue. 

UX considerations for DataGridList required natural spotlight focus, when moving from Paging controls, back to the DataGridList. Originally DataGridList would jump back to the beginning of a page when passing back focus. CMB-1706 fixed this behavior - however it introduced a problem with a use case for DataList. 

DataList relied on being a Spotlight Container, so that it could remember Spotlight position when receiving focus again. Since it was no longer a container, when spotlight would respond a control inside the DataList, the scroll position would not be used to determine nearest neighbor correctly. 

Fix.

Added an option to explicitly set instances when a viewport should be a container. DataList and DataGridList both function as intended. The default option is to use the new preference for having the viewport NOT be a spotlight container. 


Enyo-DCO-1.1-Signed-off-by: Derek Anderson <derek.anderson@lge.com>