[Epic] Support Azure Identity for Spring ecosystems for Kafka

[yiliuTo]

This is the epic to track all issues about Azure Identity support for Spring Cloud Azure Kafka.

Context

Currently Kafka developers can use Event Hubs in the same way as how they use Kafka since Event Hubs supports Kafka protocols as well. For the authentication part, native Kafka developers can use either connection string as crendentials with other security configuratiosn or use OAuth2 with customzied authentication call back handler and other security configuration.

We plan to support all Azure Identity based credentials for Spring Cloud Azure Kafka support, which includes all Azure Identity supported credential types and configuration options.

With Azure Identity-based credentials being supported, we can also achieve credential-free connection as well, which based on the ManagedIdentityCredential in Azure Identity. It can enable developers to use user-assigned/system-assigend managed identities in various Azure hosting environments to establish connection with Event Hubs via various spring ecosystems for kafka.

Deliveries

The delivery resources include:

• [FEATURE REQ] Enable Azure Identity for Spring Cloud Azure Kafka support #28708
• [FEATURE REQ] Publish reference doc for Managed Identities OAuth support in Spring Cloud Azure Kafka #28709
• [FEATURE REQ] Enhance AzureKafkaSpringCloudStreamConfiguration to Kafka Binder's source configuration #29976
• [FEATURE REQ] Publish reference doc for Azure Identity support in Spring Cloud Azure Kafka #29217
• [FEATURE REQ] Publish Quick-start doc about migrating a Spring ecosystem Kafka application to Managed Identities from connection strings #28710
• [FEATURE REQ] Publish quick-start doc about setting up a credential-free spring ecosystem kafka application with Managed Identities #28712
• Publish a reference guide on how to create and configure managed identities. #29788
• Publish a reference guide on how to deploy applications to Azure hosting environments. #29789

Move the following out from this epic:

• [FEATURE REQ] Make Azure Identity support for Kafka follow the similar code pattern as JDBC #30344

[saragluna]

Move #30344 out from this epic, and closing this issue now.