add(Friend)：添加好友相关逻辑

backend/IM_API/Configs/ServiceCollectionExtensions.cs

@@ -10,6 +10,7 @@ namespace IM_API.Configs
             services.AddAutoMapper(typeof(MapperConfig));
             services.AddTransient<IAuthService, AuthService>();
             services.AddTransient<IUserService, UserService>();
+            services.AddTransient<IFriendSerivce, FriendService>();
             services.AddSingleton<IJWTService, JWTService>();
             services.AddSingleton<IRefreshTokenService,RedisRefreshTokenService>();
             return services;