qDebug support for std::chrono

While QTBUG-51950 did introduce QDebug support for many STL compound types, there is no qDebug support for `std::chrono` types (as implemented by `operator<<`; example for duration: https://en.cppreference.com/w/cpp/chrono/duration/operator_ltlt). This makes it pretty clunky to use std::chrono types in together with QDebug as we either have to manually implement `QDebug operator<<` or manually assemble the log message (`qDebug() << some_duration.count() << "hardcoded unit"`);