Add overloads for QProcess::waitForXxx(QDeadlineTimer)

Add overloads for these functions taking std::chrono::milliseconds. This would nicely conform to the other Qt interfaces, like QTimer::setInterval(), QTimer::singleShot(), etc...

The issue may be with waitForReadyRead(), as that's the overload for virtual function.

Most probably it could be applied to QIODevice interface, too.