server-runtime should use log4j2

Currently the server uses JBoss LogManager, because that's what the WildFly server used.

It works, but the properties-based configuration is kind of clunky: it uses almost the same format as java.util.logging, but there are differences. Also not many of our users are familiar with it: WildFly has its own logging configuration in the XML, and logging.properties is auto-generated.

It would be better if we switched to log4j2 with a java.util.logging bridge.