PC3 ScrollView: Avoid importing QtQuick.Controls.2
Normally, in a QQC2 style plugin's QML code you'd avoid importing QQC2 module, since that would cause an import loop. Same thing conceptually applies here, except it wouldn't hang the app like a native QQC2 style would -- it just looks wrong, and that's about it.
Instead, we can use T (QtQuick.Templates) for attached properties access, and PlasmaComponents3.* for actual implemented components.