### 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_3 = aws_client.sqs.receive_message(
            QueueUrl=queue_url, VisibilityTimeout=0, WaitTimeSeconds=4
        )
        snapshot.match("messages-3", response_3)
        num_msgs_3 = len(response_3["Messages"])
        assert num_msgs_3 == num_msgs_1
        # p
        message_4 = "message-4"
        aws_client.sns.publish(
            TopicArn=topic_arn,
            Message=message_4,
            MessageAttributes={
                "store": {"DataType": "Number", "StringValue": "99"},
                "def": {"DataType": "Number", "StringValue": "99"},
            },
        )
        response_4 = aws_client.sqs.receive_message(
            QueueUrl=queue_url, VisibilityTimeout=0, WaitTimeSeconds=4
        )
        snapshot.match("messages-4", response_4)
        num_msgs_4 = len(response_4["Messages"])
        assert num_msgs_4 == num_msgs_3
    @pytest.mark.aws_validated
    @pytest.mark.skip_snapshot_verify(paths=["$..Attributes.SubscriptionPrincipal"])
    def test_subscribe_sqs_queue(
        self, sqs_create_queue, sns_create_topic, sns_create_s, snapshot, aws_client
    ):
        # T
        topic_arn = sns_create_topic()["TopicArn"]