Set global color schemes/themes in preferences

Not like now, just setting individual colors, e.g. background black or white in each KiCad application and then fixing the other colors to suit.

Having a choice between themes e.g. dark, light, high contrast, etc. without having to select color by color (except for custom). Only one setting, in KiCad preferences that would then change the colors in Eeschema, Pcbnew, symbol and footprint editors, etc.