### 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_
with pytest.raises(ClientError) as ex:
            aws_client.sns.publish(
                TargetArn=endpoint_arn, MessageStructure="json", Message=json.dumps(message)
            )
        assert ex.value.response["Error"]["Code"] == "InvalidParameter"
    @pytest.mark.aws_validated
    @pytest.mark.skip_snapshot_verify(paths=["$..Attributes.SubscriptionPrincipal"])
    def test_subscription_after_failure_to_deliver(
        self,
        sns_create_topic,
        sqs_create_queue,
        sqs_queue_arn,
        sqs_queue_exists,
        sns_create_s,
        sns_allow_topic_sqs_queue,
        sqs_receive_num_messages,
        snapshot,
        aws_client,
    ):
        topic_arn = sns_create_topic()["TopicArn"]
        queue_name = f"test-queue-{short_uid()}"
        queue_url = sqs_create_queue(QueueName=queue_name)
        subscription = sns_create_s(topic_arn=topic_arn, queue_url=queue_url)
        subscription_arn = subscription["SubscriptionArn"]
        dlq_url = sqs_create_queue()
        dlq_arn = sqs_queue_arn(dlq_url)
        sns_allow_topic_sqs_queue(
            sqs_queue_url=dlq_url,
            sqs_queue_arn=dlq_arn,
            sns_topic_arn=topic_arn,