feat(tenpayv2): 新增部分接口

src/SKIT.FlurlHttpClient.Wechat.TenpayV2/Extensions/WechatTenpayClientExecuteFraudExtensions.cs

@@ -0,0 +1,32 @@
+using System;
+using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
+using Flurl;
+using Flurl.Http;
+
+namespace SKIT.FlurlHttpClient.Wechat.TenpayV2
+{
+    public static class WechatTenpayClientExecuteFraudExtensions
+    {
+        /// <summary>
+        /// <para>异步调用 [POST] /risk/getpublickey 接口。</para>
+        /// <para>REF: https://pay.weixin.qq.com/wiki/doc/api/tools/mch_pay_yhk.php?chapter=24_7&index=4 </para>
+        /// </summary>
+        /// <param name="client"></param>
+        /// <param name="request"></param>
+        /// <param name="cancellationToken"></param>
+        /// <returns></returns>
+        public static async Task<Models.GetRiskPublicKeyResponse> ExecuteGetRiskPublicKeyAsync(this WechatTenpayClient client, Models.GetRiskPublicKeyRequest request, CancellationToken cancellationToken = default)
+        {
+            if (client is null) throw new ArgumentNullException(nameof(client));
+            if (request is null) throw new ArgumentNullException(nameof(request));
+
+            IFlurlRequest flurlReq = client
+                .CreateRequest(request, HttpMethod.Post, "risk", "getpublickey");
+            flurlReq.Url = Url.Parse("https://fraud.mch.weixin.qq.com/risk/getpublickey");
+
+            return await client.SendRequestWithXmlAsync<Models.GetRiskPublicKeyResponse>(flurlReq, data: request, cancellationToken: cancellationToken);
+        }
+    }
+}