TableView and ListView should get row and column delegates

ListView has a delegate to render an item, and a highlight delegate to create a highlight for the current item. Normally, the highlight is behind the items, which works well except when you want to use something like alternating row colors. In such cases, you have to give each delegate a background color, which in turn doesn't play nice with the highlight. 

TableView from QtQuickControls 1 had separate properties to rowDelegate and columnDelegate, that you could use to render a background for a row or a column. I would like to suggest to bring that feature to both ListView and QtQuick.TableView. This would separate the contents of the items in the view from their background, also making it possible to have the highlight move between the this background rowDelegate (and columnDelegate) and the item contents on top.