Use org.kde.kcmutils/org.kde.config instead of kquickcontroladdons
This way, we do not use KDeclarative, but the QML plugin provided by the relevant frameworks. Using the KAuthorized API also has the advantage, that we can call a method returning a boolean instead of a QStringList where we need to check the length later on.
Depends on frameworks/kconfig!198 (merged) and frameworks/kcmutils!146 (merged)