making change so that we can use camel-aws integration to make use of other implementations of AmazonSQS instead of tightly binding it to AmazonSQSClient.

making change so that we can use camel-aws integration to make use of
other implementations of AmazonSQS instead of tightly binding it to
AmazonSQSClient. For example this also allows us to make use of
AmazonSQSBufferedAsyncClient if we want to.