bugfix:修复Mqtt服务器详情页变量值不更新的问题，修复修改Mqtt别名后台不更新的问题，重新调整了别名的架构

DMS.Core/Models/MqttAlias.cs

@@ -35,4 +35,16 @@ public class MqttAlias
     /// 关联的MQTT服务器导航属性。
     /// </summary>
     public MqttServer MqttServer { get; set; }
+
+    public MqttAlias()
+    {
+        
+    }
+
+    public MqttAlias(int variableId, int mqttServerId, string alias)
+    {
+        VariableId = variableId;
+        MqttServerId = mqttServerId;
+        Alias = alias;
+    }
 }