better support of raw data transfer

Pilz.Net/Api/ApiServer.cs

@@ -411,6 +411,7 @@ public class ApiServer : IApiServer
         else if (result.ResultContent is byte[] resultBytes)
         {
             Log.Info("Sending raw bytes response for " + context.Request.RawUrl);
+            context.Response.ContentType = "application/octet-stream";
             context.Response.OutputStream.Write(resultBytes, 0, resultBytes.Length);
             context.Response.OutputStream.Flush();
         }
@@ -455,6 +456,10 @@ public class ApiServer : IApiServer
         if (result.Message is null)
             return new(result, null);
 
+        // Return result with raw data
+        if (result.Message is ApiRawMessage dataMsg)
+            return new(result, dataMsg.Data);
+
         // Serializer
         Log.Debug("Serialize message");
         if (serializer.Serialize(result.Message) is not string resultStr)