Add a management operation to let remote EJB clients know that a particular server is no longer capable of handling a EJB request

While looking into another issue WFLY-1313 we realized that it might be a good idea to allow admins to have some kind of management operation where they could say that a particular server will no longer accept EJB invocations (for all deployments or maybe just a specific deployment). This would then allow the admins to issue such a operation and the remote EJB clients (via the EJB client library) would then realize that, they should no longer send out requests to that server node. This way the admins can then even undeploy the deployment or shutdown the server without having to worry about EJB invocations coming in and failing in-flight due to deployment being currently undeployed.

From a EJB client library point of view, this essentially is a explicit "module unavailable" notification that the server will trigger to its connected clients.