调整数据库结构，实现消息模板管理

Atomx.Admin/Atomx.Admin.Client/Models/MessageTemplateSearch.cs

@@ -4,6 +4,8 @@
     {
         public int? Type { get; set; }
 
+        public int? Language { get; set; }
+
         public string Key { get; set; } = string.Empty;
     }
 }