Expose handler and client

Author: nvborisenko

dotnet/src/webdriver/Remote/HttpCommandExecutor.cs

@@ -221,7 +221,7 @@ protected virtual void OnSendingRemoteHttpRequest(SendingRemoteHttpRequestEventA
             this.SendingRemoteHttpRequest?.Invoke(this, eventArgs);
         }
 
-        private HttpClient CreateHttpClient()
+        protected virtual HttpClientHandler CreateHttpClientHandler()
         {
             HttpClientHandler httpClientHandler = new HttpClientHandler();
             string userInfo = this.remoteServerUri.UserInfo;
@@ -234,6 +234,13 @@ private HttpClient CreateHttpClient()
 
             httpClientHandler.Proxy = this.Proxy;
 
+            return httpClientHandler;
+        }
+
+        protected virtual HttpClient CreateHttpClient()
+        {
+            var httpClientHandler = CreateHttpClientHandler();
+
             HttpMessageHandler handler = httpClientHandler;
 
             if (_logger.IsEnabled(LogEventLevel.Trace))