This moves all background rendering of elements in the top sliding panel to use the plasma theme, making full use of themes that can be downloaded from the store, doing so decreases the usage of the Qt.GraphicalEffects import which is slow and not in Qt6. There are some layout and behavioral fixes especially in widescreen mode
a top panel can be just "half" opened showing only the top row of icons. don't duplicate the icons but dynamically fade in/out those making also possible to open the drawer completely by a single, longer swipe
