Create ClusterService to hold cluster node info

When configuring Nuxeo in cluster mode, the configuration is now done with: nuxeo.cluster.enabled= true nuxeo.cluster.nodeid=... You should specify a nuxeo.cluster.nodeid even if you don't activate clustering, as it may help debugging (in particular Stream-based Pub/Sub). Internally this is expanded into XML through a default template that does: <extension target= "org.nuxeo.runtime.cluster.ClusterService" point= "configuration" > <clusterNode id= "${nuxeo.cluster.nodeid}" enabled= "${nuxeo.cluster.enabled}" /> </extension> The previous Framework properties ( repository.clustering.enabled=true , repository.clustering.id=... ) are still available for backward compatibility. In the <repository>  extension point, the <clustering> id=  and enabled=  attributes don't exist anymore. Note that repository.clustering.delay still exists but is only meaningful for VCS when used with the legacy and deprecated JDBCClusterInvalidator (which is not the default anymore since Nuxeo 9.1 ( NXP-21801 )). It is later removed by  NXP-28891 .