QMetaType now implicitly knows how to convert any QFuture<T> to
QFuture<void> without needing to manually register a converter
function.
QtWebChannel will make use of this to transparently support QFuture<T>
return types.
[ChangeLog][QtCore][QMetaType] QMetaType now supports converting any
QFuture<T> to QFuture<void>.
Task-number: QTBUG-92903
Change-Id: Ied7e71be37c346cc3d2c274ffb0d91a6821ab4d4
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>