Adding a new constructor parameter to ConsoleHandler to let it bubble messages when the output is set at Silent verbosity level (like when using--silent in the CLI).

Messages are dropped by the ConsoleHandler down the line because of the verbosity, but they are considered as handled and so bubbling is interrupted if the handler is set with$bubble = false. The use-case is to have the messages being either printed by the ConsoleHandler (and so seen by the person running the CLI) or sent to the logging system by the next handlers, but not both.
Tweaking the$verbosityLevelMap is not perfect because EMERGENCY level can never be marked as not handled.

With this change, the behaviour is more consistent between Silent and Quiet verbosity levels.