Support message group ID for SNS handler

[nickcaballero]

The org.springframework.integration.aws.outbound.SnsMessageHandler doesn't support setting the message group ID, which is necessary for FIFO topics.

The org.springframework.integration.aws.outbound.SqsMessageHandler already implements this, as well as the deduplication ID, which is also required if content based deduplication is not enabled on the FIFO topic.

[artembilan]

That's good catch and since it looks like you are already familiar with similar solution for the SqsMessageHandler, would you mind to come back to us with respective contribution to that SnsMessageHandler?

Thank you!