Provide new api method for clearing all saved levels?

[kawing-chiu]

Sometimes I want to take full control of all levels of all loggers. For example when production environment is detected. For a certain logger it could be done by calling setLevel() on that logger directly (not really clearing, but close). However for all loggers altogether, I can't find a way to do that using the current apis.

[xmedeko]

Try to iterate over getLoggers() result.