Expose Tomcat configuration to explicitly specify a connector to register with the proxy

Configuring mod_cluster to leverage ws:// with EnableWsTunnel (mod_proxy_wstunnel) requires the Tomcat to use http instead of ajp connector.

Unlike AS7/WildFly/EAP mod_cluster integration, the Tomcat one ignores such option, i.e. there is nothing about selecting a particular connector with a connector attribute in mbeans-descriptors.xml.

<Listener className="org.jboss.modcluster.container.catalina.standalone.ModClusterListener"
loadMetricClass="org.jboss.modcluster.load.metric.impl.BusyConnectorsLoadMetric"
loadMetricCapacity="1" loadHistory="9" loadDecayFactor="2" stickySession="true"
stickySessionForce="false" stickySessionRemove="true" advertise="true"
connector="http" advertiseGroupAddress="224.0.5.12" advertisePort="61217"
/>

Suggestion: Let's add the option to the catalina integration as well.