Spring Integration KCL2 only support Fanout Consumer. Should also support Shared Consumer

[siddharthjain210]

Expected Behavior
The KCL2 library also supports shared consumer. But Spring integration uses doesn't provide a way to use KCL2 using PollingConfig when used from spring cloud stream kinesis binder.

Current Behavior

The KCLMessageDrivenChannelAdapter only supports Enhanced Fan out consumer in the KCL2 implementation. The retrieval config is by default initialized by FanOutConfig.

Context

The current implementation in Spring Cloud stream and Spring integration AWS for shared consumers doesnt guarantee balancing implicitly. For any events related to shard addition or deletion, is not implicitly handled.

[siddharthjain210]

Issue linked with the same: #235