add kcp

Src/Core/Extensions/HttpClient.cs

@@ -0,0 +1,19 @@
+using System.Net.Http;
+using System.Text;
+using System.Threading;
+using Cysharp.Threading.Tasks;
+using Newtonsoft.Json;
+
+namespace BITKit
+{
+	public static class HttpClientExtensions
+	{
+		public static async UniTask<string> PostJsonAsync(this HttpClient self, string requestUrl, object value , CancellationToken cancellationToken=default)
+		{
+			var json = JsonConvert.SerializeObject(value);
+			var content = new StringContent(json, Encoding.UTF8, "application/json");
+			var response =await self.PostAsync(requestUrl, content, cancellationToken);
+			return await response.Content.ReadAsStringAsync();
+		}
+	}
+}