Allow reconfiguring log level on a per Fiber basis

[paulcsmith]

Let's say in production you set the log level to info. Then a user reports a problem and you want to change the log level to debug just for you while you poke around.

I am not sure what the API looks like but I'd almost want to do something like

if params.get?(:enable_super_special_log_just_for_me)
  Log.current_fiber_level = :debug # Sets all logs to `:debug` *just* for the current Fiber
end

In a handler, before pipe, whatever. This would be super handy and I'd like to build something in for this at some point. So you can use Breeze in production but just with a special token set in the query param or a header