clazy should help with metatype changes in Qt 6

There were a few changes to QMetaType and QVariant where additional tooling would be helpful:

• QMetaType(QMetaType::Int)/QMetaType(QVariant::Int) should become QMetaType::fromType<int>(); same for the other QMetaType::Type values
• variant.metaType().id() should be simplified to variant.userType(); except when its inside a QMetaType constructor: QMetaType type = QMetaType(variant.metaType().id()) should simply become QMetaType type = variant.metaType() .