fix #167; include the original exception in .Status.DebugException (simpler than expected!)

Author: mgravell

src/protobuf-net.Grpc/Configuration/SimpleRpcExceptionsInterceptor.cs

@@ -112,7 +112,7 @@ internal static bool ShouldWrap(Exception exception, out Status status)
                 TimeoutException i => StatusCode.DeadlineExceeded,
 #pragma warning restore IDE0059 // needs more recent compiler than the CI server has
                 _ => StatusCode.Unknown,
-            }, exception.Message);
+            }, exception.Message, exception);
             return true;
         }