### Is there an existing issue for this?

- [X] I have searched the existing issues

### Feature description

SNS allows for the publishing of messages to an SMS destination with a phone number. Those messages are logged and stored in the `SnsStore`, but there is no way to retrieve them for verification. The request here is to expose a new endpoint which returns SMS messages from the store, similar to the one made available to retrieve email messages sent via SES.

### 🧑‍💻 Implementation

The `SNSServicePlatformEndpointMessagesApiResource` class makes endpoints available for accessing platform endpoint messages sent via SNS. A similar resource class could be implemented to provide new endpoints for accessing SMS messages.

Given that interaction platform endpoint messages is exposed at the path `/_aws/sns/platform-endpoint-messages`, SMS message interaction would presumably be exposed at `/_aws/sns/sms-messages`. A `GET` endpoint could accept an optional `phoneNumber` query parameter to filter messages based on the destination phone number.

```python
class SNSServiceSMSMessagesApiResource:
  @route(sns_constants.SMS_MSGS_ENDPOINT, methods=["GET"])
    def on_get(self, request: Request):
      account_id = #...
      region = #...
      filter_phone_number = request.args.get("phoneNumber")
      # get store; conditionally filter messages based on filter_phone_number
```

### Anything else?

_No response_
"Message": "Test Message with one attribute",
                "Subject": "Subject",
                "MessageAttributes": {"attr1": {"DataType": "Number", "StringValue": "19.12"}},
                "MessageDeduplicationId": "MessageDeduplicationId-2",
            },
            {
                "Id": "3",
                "MessageGroupId": message_group_id,
                "Message": "Test Message without attribute",
                "Subject": "Subject",
                "MessageDeduplicationId": "MessageDeduplicationId-3",
            },
        ]
        publish_batch_response = aws_client.sns.publish_batch(
            TopicArn=topic_arn,
            BatchRequestEntries=publish_batch_request_entries,
        )
        snapshot.match("publish-batch-response-fifo", publish_batch_response)
        assert "Successful" in publish_batch_response
        assert "Failed" in publish_batch_response
        for successful_resp in publish_batch_response["Successful"]:
            assert "Id" in successful_resp
            assert "MessageId" in successful_resp
        message_ids_received = set()
        messages = []
        def get_messages_from_dlq(amount_msg: int):
            # d
            # M
            sqs_response = aws_client.sqs.receive_message(
                QueueUrl=dlq_url,