* 99% 1:1 wrapper of the underlying quarkus gelf extension.
* excluded `filter-stack-trace` and `stack-trace-throwable-reference` options for now, as they are either undocumented on the quarkus side or not important imo.
* added docs and examples for Graylog and ELK stack
* NOT added an automated test, as this is really a 1:1 wrapper around the extension, Test setup would be cumbersome, test would take too much time and tests are done in quarkus itself.
Closes#12125
Changes behaviour to:
- all raw quarkus config properties are handled as runtime config in keycloak, with the exception of raw properties we need for additional datasources, there we check for build- vs runtime
- unknown quarkus buildtime properties require a build first or the usual quarkus warning is shown
- wrapped quarkus properties still get ignored / overwritten by our configuration layer (no change in behaviour here)
Closes#10968
