Describe the story

Create a DynamoDBClient which serves as a wrapper around the AWS SDK DynamoDBClient and DynamoDBDocumentClient.

Acceptance criteria

GIVEN the app is constructing an instance of the DynamoDB client
WHEN no parameters are supplied to the constructor
THEN an instance of the client is created using the default configuration for the DynamoDBClient and the DynamoDBDocumentClient

WHEN the DynamoDBClientConfig is provided to the constructor
THEN the DyanamoDBClient instance is constructed using the supplied configuration

WHEN the marshallOptions are provided to the constructor
THEN the DynamoDBDocumentClient is constructed using the supplied configuration

WHEN the unmarshallOptions are provided to the constructor
THEN the DynamoDBDocumentClient is constructed using the supplied configuration

WHEN the DynamoDBClient and DynamoDBDocumentClient instances are constructed
THEN they are cached as singleton instances

Additional context

Add any other context about the story here.