Fix session pump stops on some exceptions

[inech]

Reproduction:

1. Send some messages with different sessions to a queue.
2. Register the session handler sessionClient.RegisterSessionHandler(MessageHandler, new SessionHandlerOptions(ExceptionReceivedHandler) {MaxConcurrentSessions = 1, MessageWaitTimeout = TimeSpan.FromSeconds(5)});
3. See messages being processed.
4. Disable the queue.
5. See some exceptions happening.
6. After some time enable the queue.
7. Expected: Session handler continues to process messages. Actual: Session handler is stuck until recreated.

P.S. For non-sessioned queues it works correctly. When using queueClient.RegisterMessageHandler(MessageHandler...) and then disabling & enabling it the queue, message processing continues as expected. This PR implements the same behavior for sessioned-queues.

[azuresdkci]

Can one of the admins verify this patch?

[jsquire]

Merging per request from Neeraj.