### 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_
response = sns_secondary_client.get_topic_attributes(TopicArn=topic_arn)
        assert response["Attributes"]["DisplayName"] == "xenon"
        assert sns_secondary_client.add_permission(
            TopicArn=topic_arn,
            Label="foo",
            AWSAccountId=["666666666666"],
            ActionName=[""],
        )
        assert sns_secondary_client.remove_permission(TopicArn=topic_arn, Label="foo")
        assert sns_secondary_client.publish(TopicArn=topic_arn, Message="hello world")
        subscription_arn = sns_secondary_client.subscribe(
            TopicArn=topic_arn, Protocol="email", Endpoint="devil@hell.com"
        )["SubscriptionArn"]
        response = sns_secondary_client.list_subscriptions_by_topic(TopicArn=topic_arn)
        subscriptions = [s["SubscriptionArn"] for s in response["Subscriptions"]]
        assert subscription_arn in subscriptions
        assert sns_secondary_client.delete_topic(TopicArn=topic_arn)
    def test_cross_account_publish_to_sqs(
        self,
        sns_primary_client,
        sns_secondary_client,
        sqs_primary_client,
        sqs_secondary_client,
        sqs_queue_arn,
    ):
        """
        This test validates that we can publish to SQS queues that are not in the default account, and that another
        account can p as well
        Note: we are not setting Queue policies here as it's only in localstack and IAM is not enforced, for the sake
        of simplicity