添加用户和Mqtt的仓储文件，添加的对Excel进行导入导出功能，并完成单元测试

Data/Repositories/MqttRepository.cs

@@ -0,0 +1,75 @@
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using PMSWPF.Data.Entities;
+
+namespace PMSWPF.Data.Repositories;
+
+/// <summary>
+/// Mqtt仓储类，用于操作DbMqtt实体
+/// </summary>
+public class MqttRepository
+{
+    /// <summary>
+    /// 根据ID获取Mqtt配置
+    /// </summary>
+    /// <param name="id">主键ID</param>
+    /// <returns></returns>
+    public async Task<DbMqtt> GetByIdAsync(int id)
+    {
+        using (var _db = DbContext.GetInstance())
+        {
+            return await _db.Queryable<DbMqtt>().In(id).SingleAsync();
+        }
+    }
+
+    /// <summary>
+    /// 获取所有Mqtt配置
+    /// </summary>
+    /// <returns></returns>
+    public async Task<List<DbMqtt>> GetAllAsync()
+    {
+        using (var _db = DbContext.GetInstance())
+        {
+            return await _db.Queryable<DbMqtt>().ToListAsync();
+        }
+    }
+
+    /// <summary>
+    /// 新增Mqtt配置
+    /// </summary>
+    /// <param name="mqtt">Mqtt实体</param>
+    /// <returns></returns>
+    public async Task<int> AddAsync(DbMqtt mqtt)
+    {
+        using (var _db = DbContext.GetInstance())
+        {
+            return await _db.Insertable(mqtt).ExecuteReturnIdentityAsync();
+        }
+    }
+
+    /// <summary>
+    /// 更新Mqtt配置
+    /// </summary>
+    /// <param name="mqtt">Mqtt实体</param>
+    /// <returns></returns>
+    public async Task<int> UpdateAsync(DbMqtt mqtt)
+    {
+        using (var _db = DbContext.GetInstance())
+        {
+            return await _db.Updateable(mqtt).ExecuteCommandAsync();
+        }
+    }
+
+    /// <summary>
+    /// 根据ID删除Mqtt配置
+    /// </summary>
+    /// <param name="id">主键ID</param>
+    /// <returns></returns>
+    public async Task<int> DeleteAsync(int id)
+    {
+        using (var _db = DbContext.GetInstance())
+        {
+            return await _db.Deleteable<DbMqtt>().In(id).ExecuteCommandAsync();
+        }
+    }
+}