KeyRing and CMM get the original DDB request object through GetEncryptionMaterialsInput / OnEncryptInput / GetDecryptionMaterialsInput / OnDecryptInput

[abrav9595]

In S3EncryptionClient we are able to access ExecutionAttributes added to the AwsRequest object through this. We want to follow the same format for DDB here so we can pass state per request through ExecutionAttributes , per request call.