feat: add Azure Service Bus messaging provider

[atharva-nagane]

Summary

Azure has no app_services module in RustCloud at all. Azure Service Bus
is Azure's enterprise messaging backbone and the direct equivalent of AWS SQS
(recently added in this repo). Adding it brings Azure to parity with AWS
on messaging infrastructure.

Proposed changes

Create the first Azure app_services module by adding azure_service_bus.rs
under azure/azure_apis/app_services/ with:

• create_queue / delete_queue / list_queues — queue lifecycle management
• send_message — publish to a queue or topic
• receive_message — destructive read (receive-and-delete, at-most-once)
• peek_lock_message — non-destructive lock for at-least-once processing
• complete_message — delete a locked message after processing

Uses AZURE_SERVICEBUS_NAMESPACE + AZURE_SERVICEBUS_TOKEN env vars.
No new Cargo dependencies.