### 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_
wait_for_port_closed(server.port)
        aws_client.sns.publish(
            TopicArn=topic_arn,
            Message=json.dumps({"message": "test_redrive_policy"}),
        )
        response = aws_client.sqs.receive_message(QueueUrl=dlq_url, WaitTimeSeconds=10)
        assert (
            len(response["Messages"]) == 1
        ), f"invalid number of messages in DLQ response {response}"
        message = json.loads(response["Messages"][0]["Body"])
        assert message["Type"] == "Notification"
        assert json.loads(message["Message"])["message"] == "test_redrive_policy"
    @pytest.mark.aws_validated
    def test_redrive_policy_lambda_subscription(
        self,
        sns_create_topic,
        sqs_create_queue,
        sqs_queue_arn,
        create_lambda_function,
        lambda_su_role,
        sns_subscription,
        sns_allow_topic_sqs_queue,
        snapshot,
        aws_client,
    ):
        dlq_url = sqs_create_queue()
        dlq_arn = sqs_queue_arn(dlq_url)
        topic_arn = sns_create_topic()["TopicArn"]
        sns_allow_topic_sqs_queue(
            sqs_queue_url=dlq_url, sqs_queue_arn=dlq_arn, sns_topic_arn=topic_arn