### 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 = aws_client.sqs.receive_message(
                QueueUrl=queue_url,
                VisibilityTimeout=0,
                WaitTimeSeconds=5 if is_aws_cloud() else 2,
            )
            snapshot.match(f"recv-passed-msg-{i}", response)
            receipt_handle = response["Messages"][0]["ReceiptHandle"]
            aws_client.sqs.delete_message(QueueUrl=queue_url, ReceiptHandle=receipt_handle)
        # p
        messages = [
            {"object": {"key": "test-auto"}},
            {"object": {"key": "auto-test"}, "test": "just-exists"},
            {"object": {"key": "auto-test", "nested_key": "just-exists"}},
            {"object": {"test": "auto-test"}},
            {"test": "auto-test"},
        ]
        for message in messages:
            aws_client.sns.publish(
                TopicArn=topic_arn,
                Message=json.dumps(message),
            )
        response = aws_client.sqs.receive_message(
            QueueUrl=queue_url, VisibilityTimeout=0, WaitTimeSeconds=5 if is_aws_cloud() else 2
        )
        # a
        assert "Messages" not in response
        # p
        message = "Regular string message"
        aws_client.sns.publish(
            TopicArn=topic_arn,