Race condition in AzureServiceBusQueue when multiple processes are creating the same queue

[moswald]

Right now, EnsureQueueCreatedAsync will check if the queue exists, and then if not, it will try to create it. If another process creates the queue in-between these two calls, then the create fails with a MessagingEntityAlreadyExistsException. This is caught and handled and works fine.

However, there's a catch - if another process is currently creating the queue, then it will fail with MessagingException, which is not caught.

The error seen in logs is:

Microsoft.ServiceBus.Messaging.MessagingException: The remote server returned an error: (409) Conflict. SubCode=40901. Another conflicting operation is in progress.

Since MessagingEntityAlreadyExistsException derives from MessagingException, the solution is to catch MessagingException instead.

[moswald]

Fixed by #46