Add a new constructor overload to AzureServiceBusTransport that doesn't require specifying the topology

[stevedowling]

Describe the suggested improvement

Is your improvement related to a problem? Please describe.

The only construction available at the moment requires specifying a topology even if the default topology is going to be used. This is non-intuitive and seems unnecessary.

Describe the suggested solution

Add a new constructor overload to AzureServiceBusTransport that doesn't require specifying the topology with a fall back to TopicTopology.Default.

Describe alternatives you've considered

None

Additional Context

No response

[mikeminutillo]

Note that the topology was made mandatory when we introduced a new topology in transport version 5.

Although the new topology is a good default for new projects, it will not work for integration with pre-existing endpoints running on the old topology.