### Description

I want to add support of a separate AWS connection for DynamoDB in `DynamoDBToS3Operator` in `apache-airflow-providers-amazon` via `aws_dynamodb_conn_id` constructor argument.



### Use case/motivation

Sometimes DynamoDB tables and S3 buckets live in different AWS accounts so to access both resources you need to assume a role in another account from one of them.
That role can be specified in AWS connection, thus we need to support two of them in this operator.

### Related issues

_No response_

### Are you willing to submit a PR?

- [X] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

"""Custom json encoder implementation"""
    def default(self, obj):
        """Convert decimal objects in a json serializable format."""
        if isinstance(obj, Decimal):
            return float(obj)
        return super().default(obj)
def _convert_item_to_json_bytes(item: dict[str, Any]) -> bytes:
    return (json.dumps(item, cls=JSONEncoder) + "\n").encode("utf-8")
def _upload_file_to_s3(
    file_obj: IO, bucket_name: str, s3_key_prefix: str, aws_conn_id: str = "aws_default"
) -> None:
    s3_client = S3Hook(aws_conn_id=aws_conn_id).get_conn()
    file_obj.seek(0)
    s3_client.upload_file(
        Filename=file_obj.name,
        Bucket=bucket_name,
        Key=s3_key_prefix + str(uuid4()),
    )
class DynamoDBToS3Operator(BaseOperator):