+act,slf #11715 Add configurable LoggingFilter

* The filter is used by the LoggingAdapter before publishing
  to the event bus
* Slf4jLoggingFilter uses backend log level configuration
  (e.g. logback.xml)
Merge pull request #15413 from akka/wip-11715-logging-filter-patriknw

+act,slf #11715 Add configurable LoggingFilter