reduce set of known types to import set

Code like this not cause any problem for qmllint:

import QtQuick 2.11
import QtQuick.Window 2.3


Text {
    opacity: 1 - Tumbler.displacement
}

but if run this code I get bunch of warnings:

unknown:24: qrc:/utils/TumblerDelegate.qml:6: ReferenceError: Tumbler is not defined

This is because of code missed "import QtQuick.Controls 2.4", but qmllint failed to notice this.