Auto format: duration

[3Hren]

Given a std::chrono::duration value: const std::chrono::seconds value(1);

Suggest some way to auto format both pattern placeholders and attributes when provided values of such type. For example:

logger.log(4, "elapsed: {}", std::chrono::seconds(1), attribute_list{
    "duration", std::chrono::seconds(100)
});

@shindo you might be interested.