【新增】增加【用户提现】功能开关，前端根据设置限制访问，同时优化充值后台设置后前端的限制。

CoreCms.Net.Configuration/SystemSettingConstVars.cs

@@ -536,6 +536,10 @@ namespace CoreCms.Net.Configuration
         /// </summary>
         public const string ShowStoreBalanceRechargeSwitch = "showStoreBalanceRechargeSwitch";
 
+        /// <summary>
+        /// 是否允许提现
+        /// </summary>
+        public const string IsAllowWithdrawCash = "isAllowWithdrawCash";
 
         /// <summary>
         /// 显示增值服务板块