kcm/ui: add required id and parentLayout property

For correct alignment with wallpaper config, an ancestor node must have id "appearanceRoot" and property "parentLayout". See the files plasma-workspace/wallpapers/image/

• imagepackage/contents/ui/config.qml
• slideshowpackage/contents/ui/SlideshowComponent.qml

BUG: 478599 FIXED-IN: 6.0

Before:

After:

See also plasma-workspace!3694 (merged)