Currently queues are lazy on operations with messages, but not with
subscriptions. It means the user is forced to pre-create a queue before
creating a subscription to the queue, which is not very convenient.
Also currently if a queue has a subscription, the subscription will
stay on even if the user will delete the queue. But even if so Zaqar
will still work normally. This is strange that subscriptions can exist
with deleted corresponding queues, but it's impossible to create a
subscription to yet unexising queue.
This patch makes queues lazy also on operations with subscriptions, so
the user will be able to subscribe to yet unexisting queue.
Also this patch modifies tests, to make sure Zaqar's subscriptions
work both with pre-created queues and non-existing queues.
APIImpact
DocImpact
Implements: blueprint lazy-queues-in-subscriptions
Change-Id: I814b503243c4e06e74acc6b709bda4269df889e9
4c2b7e04db