Replace removed QDateTime constructor with new function
This constructor https://doc.qt.io/qt-5/qdatetime.html#QDateTime-1 is not present in Qt6 QDateTime
https://doc.qt.io/qt-6/qdatetime.html.
So to create similar objects in new Qt as before, we use QDate::startOfDay()
.
So this patch has new global function to create QDateTime
objects both in old and new Qt.
Behavior is same as before
Edited by Anjani Kumar