### 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_
for client, queue_url in (
                (sqs_primary_client, queue_1_url),
                (sqs_secondary_client, queue_2_url),
            ):
                response = client.receive_message(
                    QueueUrl=queue_url,
                    VisibilityTimeout=0,
                    WaitTimeSeconds=5,
                )
                messages = response["Messages"]
                assert len(messages) == 1
                assert topic_1_arn in messages[0]["Body"]
                assert message_content in messages[0]["Body"]
                client.delete_message(
                    QueueUrl=queue_url, ReceiptHandle=messages[0]["ReceiptHandle"]
                )
        get_messages_from_queues("TestMessageOwner")
        # a
        sns_secondary_client.publish(TopicArn=topic_1_arn, Message="TestMessageSecondary")
        get_messages_from_queues("TestMessageSecondary")