[service-bus] ServiceBusClient top-level object

[richardpark-msft]

Track 2 SDKs all have a top-level ServiceBusClient that represents the connection to the Service Bus instance. All links (sender, receiver) are created using this client.

There are some key components to this class:

• ServiceBus client should accept Azure Identity as an authentication mechanism #15638
• It accepts connection strings at the broker level and at the entity path level
• There are 4 paths to creating an AMQP link using the ServiceBusClient:
  • CreateReceiverFor(Queue|Subscription)() - creates a non-session-based receiver link to an entity. The connection/link are opened lazily when using this method (ie, on first link access).
  • CreateSender() - creates a sender to a topic or queue. The connection/link are opened lazily when using this method (ie, on first link access).
  • (Moved to [service-bus] Sending and receiving messages using sessions #15163) AcceptSessionFor(Queue|Subscription)() - accepts a session from a session-based entity with a specific ID. This method is not lazy - the link is opened in this call.
  • (Moved to [service-bus] Sending and receiving messages using sessions #15163) AcceptNextSession(Queue|Subscription) - accepts the next available session from a session-based entity.
• The client itself can be closed, which also closes any links that have been created from it.

The concept of having top level objects that refer to entities is no longer needed.

[richardpark-msft]

Logged sessions under a separate issue: #15163

All other work for this has been completed.