optimize publication state queries

Document publishing state look-up is now based on ACL by default. You can select the task based look-up by contributing a new factory to the publisher service. That factory will sub-class the org.nuxeo.ecm.platform.publisher.task.CoreProxyWithWorkflowFactory and initialize the field lookupState to an instance of class org.nuxeo.ecm.platform.publisher.task.LookupStateByTask. If needed, you can select the state look-up strategy when you're requesting a publication tree org.nuxeo.ecm.platform.publisher.api.PublisherService.getPublicationTree by setting the property 'stateLookup' in the parameter map to 'byACL' or 'byTask'. The corresponding constants are defined in CoreProxyWithWorkflowFactory.