refactor: simplify server & service manipulation (#993)

* refactor: simplify server & service manipulation

* update

* fix

* update for nat, ddns & notification

* chore

* update cron

* update dependencies

* use of function iterators

* update default dns servers

cmd/dashboard/controller/fm.go

@@ -32,9 +32,7 @@ func createFM(c *gin.Context) (*model.CreateFMResponse, error) {
 		return nil, err
 	}
 
-	singleton.ServerLock.RLock()
-	server := singleton.ServerList[id]
-	singleton.ServerLock.RUnlock()
+	server, _ := singleton.ServerShared.Get(id)
 	if server == nil || server.TaskStream == nil {
 		return nil, singleton.Localizer.ErrorT("server not found or not connected")
 	}