windows: force sane style, color, icons
there's various weird issues to do with the defaults in frameworks not kicking in reliably and debugging this is a bit of a nightmare. instead force suitable values
this notably fixes:
- radio buttons, check boxes and sliders being incorrectly scaled, by using the breeze style
- the icons not coloring correctly, by forcing breeze icon theme
- the colors not adapting correctly to system theme changes, by ensuring we have a kcolorschememanager