Add divider and background features to TableView

As of now when we want a divider between rows and columns or a background color on a row or column we have to implement that in each cell delegate.

On top of the poor usability in the code, it doesn't seem optimized.

For example if we have a 100 rows 10 columns table where we want to have alternating row color we will end up with 100 * 10 / 2 (assuming no background for every other row) = 500 Rectangles.
If that feature was added in TableView it could be brought down to 50 Rectangles (one for every other row).
The same can be said for divider/grids between rows/columns.

It would also improve the API:
Current:

delegate: Label {
    text: model.display
    background: Rectangle { visible: row % 2 === 1; color:  "lightgray" } // couldn't figure out how to do a null background so I guess that bumps up the number of background Rectangles to 1000
}

Potential future implementation:

delegate: Label {
    text: model.display
}
rowBackgroundDelegate: Rectangle { visible: row % 2 === 1; color:  "lightgray" }

For dividers the current code is more cumbersome:

delegate: Label {
    text: model.display
    Rectangle { height: 1; width: parent.width; anchors.bottom: parent.bottom; color: "lightgray" }
}

And what if I don't want to show a divider on the last row? Should I query the row count in the cell delegate and conditionally hide the divider? That seems like a complex binding.

Things get even more complicated when you want to provide a reusable component based on TableView. Moving those out of the cell delegate and providing it as a base TableView support would greatly help.
One could easily add a pair of rowBackgroundColor and alternatingRowBackgroundColor there and define the rowBackgroundDelegate based on those if we want to keep the TableView API as simple as possible.