FedEx provider refactoring

src/CachedRateRequestData.cs

@@ -0,0 +1,15 @@
+using System.Collections.Generic;
+
+namespace Dynamicweb.Ecommerce.ShippingProviders.FedEx;
+
+/// <summary>
+/// Structure that is used while calculating shipping fee for the specified order in FedEx shipping provider
+/// </summary>
+internal struct CachedRateRequestData
+{
+    public string Request;
+    public double Rate;
+    public string Currency;
+    public List<string> Errors;
+    public List<string> Warning;
+}