Feature/651 outsource crypto

Merge Request for planning#651 (closed)

DemoRunner/SenderDemo.cs

+using System.Threading.Channels;
 using FitConnect;
 using FitConnect.Models;
 using Microsoft.Extensions.Configuration;
@@ -29,9 +30,9 @@ public static class SenderDemo {
         var destinationId = config["FitConnect:Sender:DestinationId"];
         var leikaKey = config["FitConnect:Sender:LeikaKey"];
 
-        Client
+        var sender = Client
             .GetSender(FitConnectEnvironment.Testing, clientId, clientSecret, logger)
-            .WithDestination(destinationId)
+            .WithDestination(destinationId, (key) => Console.WriteLine(key))
             .WithServiceType("FIT Connect Demo", leikaKey)
             .WithEncryptedAttachments(new Dictionary<string, string>())
             .WithEncryptedMetaData("")