### 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_
snapshot.match("list-after-update-tags", tags)
    @pytest.mark.only_localstack
    def test_topic_email_subscription_confirmation(
        self, sns_create_topic, sns_subscription, aws_client
    ):
        # F
        # c
        # f
        topic_arn = sns_create_topic()["TopicArn"]
        subscription = sns_subscription(
            TopicArn=topic_arn,
            Protocol="email",
            Endpoint="localstack@yopmail.com",
        )
        subscription_arn = subscription["SubscriptionArn"]
        parsed_arn = parse_arn(subscription_arn)
        store = SnsProvider.get_store(parsed_arn["account"], parsed_arn["region"])
        sub_attr = aws_client.sns.get_subscription_attributes(SubscriptionArn=subscription_arn)
        assert sub_attr["Attributes"]["PendingConfirmation"] == "true"
        def check_subscription():
            for token, sub_arn in store.subscription_tokens.items():
                if sub_arn == subscription_arn:
                    aws_client.sns.confirm_subscription(TopicArn=topic_arn, Token=token)
            sub_attributes = aws_client.sns.get_subscription_attributes(
                SubscriptionArn=subscription_arn
            )
            assert sub_attributes["Attributes"]["PendingConfirmation"] == "false"
        retry(check_subscription, retries=PUBLICATION_RETRIES, sleep=PUBLICATION_TIMEOUT)
    @pytest.mark.aws_validated
    def test_sqs_topic_subscription_confirmation(