ExternalManagementRequestExecutor not properly tracked by ContainerStateMonitor

ExternalManagementRequestExecutor is an ON_DEMAND service installed by HostControllerService and ApplicationServerService. Because it is installed by the parent of the AbstractControllerService impls, it is not tracked by ContainerStateMonitor. However, because it is ON_DEMAND it's also not started when a management op adding an http management interface adds dependencies. The results is CSM can get out of whack, seeing the http management interface as in PROBLEM state (because their dep on ExternalManagementRequestExecutor is not yet satisfied), but also seeing itself as having reached stability, because all tracked controllers are in a rest state. The result is invalid service verification failures like I'm seeing on https://github.com/wildfly/wildfly-core/pull/3109.

This is a bit of a pain to sort as we don't want to make the service ACTIVE (since it's not needed without an http management interface) and it's messy to integrate ExternalManagementRequestExecutor with the monitor controlled by AbstractControllerService's ModelControllerImpl.