### 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_
)["TopicArn"]
        queue_url = sqs_create_queue(
            QueueName=queue_name,
            Attributes=queue_attributes,
        )
        sns_create_s(topic_arn=topic_arn, queue_url=queue_url)
        message = "Test"
        kwargs = {"MessageGroupId": "message-group-id-1"}
        if not content_based_deduplication:
            kwargs["MessageDeduplicationId"] = "message-deduplication-id-1"
        aws_client.sns.publish(TopicArn=topic_arn, Message=message, **kwargs)
        response = aws_client.sqs.receive_message(
            QueueUrl=queue_url,
            WaitTimeSeconds=10,
            AttributeNames=["All"],
        )
        snapshot.match("messages", response)
        aws_client.sqs.delete_message(
            QueueUrl=queue_url, ReceiptHandle=response["Messages"][0]["ReceiptHandle"]
        )
        # r
        aws_client.sns.publish(TopicArn=topic_arn, Message=message, **kwargs)
        response = aws_client.sqs.receive_message(
            QueueUrl=queue_url,
            WaitTimeSeconds=1,
            AttributeNames=["All"],
        )
        snapshot.match("dedup-messages", response)
    @pytest.mark.aws_validated
    def test_validations_for_fifo(