cmd/cli: log validate remote config during "ctrld restart"

The same manner with what ctrld is doing for "ctrld start" command.

cmd/cli/control_server.go

@@ -178,6 +178,7 @@ func (p *prog) registerControlServerHandler() {
 	p.cs.register(cdPath, http.HandlerFunc(func(w http.ResponseWriter, request *http.Request) {
 		if cdUID != "" {
 			w.WriteHeader(http.StatusOK)
+			w.Write([]byte(cdUID))
 			return
 		}
 		w.WriteHeader(http.StatusBadRequest)