SimpleKCM: port header to Kirigami.Padding
This fixes headerPaddingEnabled: false not working, as currently the header always shows padding no matter what. We have a dedicated Kirigami thing to control this; let's use it.
This fixes headerPaddingEnabled: false not working, as currently the header always shows padding no matter what. We have a dedicated Kirigami thing to control this; let's use it.