Loads an object from DynamoDB for the given hash-and-range primary key.
            
            Uses DynamoDBContextConfig configured on the context.
            Type must be marked up with DynamoDBTableAttribute and at least
            one public field/property with DynamoDBHashKeyAttribute.
            
 Generic Template Parameters
 Generic Template Parameters- T
- Type to populate.
 Return Value
 Return Value
            Object of type T, populated with properties of item loaded from DynamoDB.