Bug 1923: Automatically close timed out Session

https://winscp.net/tracker/1923
(cherry picked from commit 46f2afbd34a233360c674c65de0b190795c0e134)

Source commit: 02a531fe3e214e282473a45bd494b6107ba6ac39

dotnet/Session.cs

@@ -2268,6 +2268,7 @@ namespace WinSCP
                 {
                     _logReader.SetTimeouted();
                 }
+                Cleanup();
                 throw Logger.WriteException(new TimeoutException(message));
             }