
Improve support for MBeans without a backing endpoint by introducing a `JmxEndpoint` interface. The `JmxEndpoint` is intentionally similar in design to the `MvcEndpoint` from the `mvc` package and allows for completely custom JMX beans that are not backed by any real actuator `Endpoint`. The `AuditEventsMBean` has been refactored to use the new interface and has been renamed to `AuditEventsJmxEndpoint`. See gh-6579