Pass PostData to BoundConfigurationContent when TransferEncodingChunked is enabled (#189)

As titled.

Closes #188

Author: flobernd

src/Elastic.Transport/Components/TransportClient/Content/RequestDataContent.cs

@@ -66,9 +66,10 @@ private static void OnStreamAvailable(BoundConfiguration boundConfiguration, Pos
 	}
 
 	/// <summary> Constructor used in asynchronous paths. </summary>
-	public BoundConfigurationContent(BoundConfiguration boundConfiguration, CancellationToken token)
+	public BoundConfigurationContent(BoundConfiguration boundConfiguration, PostData? postData, CancellationToken token)
 	{
 		_boundConfiguration = boundConfiguration;
+		_postData = postData;
 		_token = token;
 
 		Headers.TryAddWithoutValidation("Content-Type", boundConfiguration.ContentType);

src/Elastic.Transport/Components/TransportClient/HttpRequestInvoker.cs

@@ -462,7 +462,7 @@ private static void SetContent(HttpRequestMessage message, BoundConfiguration bo
 	private static async Task SetContentAsync(HttpRequestMessage message, BoundConfiguration boundConfiguration, PostData postData, CancellationToken cancellationToken)
 	{
 		if (boundConfiguration.TransferEncodingChunked)
-			message.Content = new BoundConfigurationContent(boundConfiguration, cancellationToken);
+			message.Content = new BoundConfigurationContent(boundConfiguration, postData, cancellationToken);
 		else
 		{
 			var stream = boundConfiguration.MemoryStreamFactory.Create();