CancellationReason missing Item

[knap1930]

When sending "ReturnValuesOnConditionCheckFailure": "ALL_OLD" for a transaction, there is no way to access the item that failed the condition check. here is an example response copied from getmoto/moto#5204

{'CancellationReasons': [{'Code': 'ConditionalCheckFailed',
                          'Item': {'customer': {'S': 'mark'},
                                   'lock': {'M': {'acquired_at': {'N': '123'}}},
                                   'mealtime': {'S': 'breakfast'}},
                          'Message': 'The conditional request failed'}],
 'Error': {'Code': 'TransactionCanceledException',
           'Message': 'Transaction cancelled, please refer cancellation '
                      'reasons for specific reasons [ConditionalCheckFailed]'},
 'Message': 'Transaction cancelled, please refer cancellation reasons for '
            'specific reasons [ConditionalCheckFailed]',
 'ResponseMetadata': {'HTTPHeaders': {'connection': 'keep-alive',
                                      'content-length': '393',
                                      'content-type': 'application/x-amz-json-1.0',
                                      'date': 'Wed, 08 Jun 2022 18:55:51 GMT',
                                      'server': 'Server',
                                      'x-amz-crc32': '947576560',
                                      'x-amzn-requestid': 'BDBL292TOK52OSPP0GTJTTS2CVVV4KQNSO5AEMVJF66Q9ASUAAJG'},
                      'HTTPStatusCode': 400,
                      'RequestId': 'BDBL292TOK52OSPP0GTJTTS2CVVV4KQNSO5AEMVJF66Q9ASUAAJG',
                      'RetryAttempts': 0}}