qmlsc: Add generate_CmpInstanceOf support

import QtQuick
import QtQuick.Window

Window {
    width: 640
    height: 480
    visible: true
    title: qsTr("Hello World")

    Item {
        id: foo
    }

    Component.onCompleted: {
        const fooIsItem = foo instanceof Item
        console.log("foo is item: " + fooIsItem)
    }
}