Azure Cosmos Kafka Connector: Add AAD Support

[xinlian12]

Summary

Add Azure Active Directory (AAD) authentication support in the Azure Cosmos DB Kafka Connector.

Description

Start with ServicePrincipalName as the initial AAD authentication method to enable secure, identity-based access to Cosmos DB from the Kafka Connector.

Requirements

• Implement AAD authentication support in the Cosmos DB Kafka Connector
• Begin with ServicePrincipalName-based authentication
• Ensure backward compatibility with existing key-based authentication
• Update documentation and configuration examples

[github-actions]

Thanks for the feedback! We are routing this to the appropriate team for follow-up. cc @kushagraThapar @pjohari-ms @TheovanKraay.