kcms/colors: Provide QPalette colors via an extension type
In Qt5 passing a QPalette to QML was working automagically but this is no longer the case. Provide properties for all the colors via an extension type. BUG:471434
In Qt5 passing a QPalette to QML was working automagically but this is no longer the case. Provide properties for all the colors via an extension type. BUG:471434