### 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_
assert subscribe_url == (
            f"{service_url}/?Action=ConfirmSubscription&TopicArn={topic_arn}&Token={token}"
        )
        test_broken_confirm_url = (
            f"{service_url}/?Action=ConfirmSubscription&TopicArn=not-an-arn&Token={token}"
        )
        broken_confirm_subscribe_request = requests.get(test_broken_confirm_url)
        snapshot.match(
            "broken-topic-arn-confirm",
            _get_snapshot_requests_response(broken_confirm_subscribe_request),
        )
        test_broken_token_confirm_url = (
            f"{service_url}/?Action=ConfirmSubscription&TopicArn={topic_arn}&Token=abc123"
        )
        broken_token_confirm_subscribe_request = requests.get(test_broken_token_confirm_url)
        snapshot.match(
            "broken-token-confirm",
            _get_snapshot_requests_response(broken_token_confirm_subscribe_request),
        )
        # u
        parsed_arn = parse_arn(topic_arn)
        different_region = "eu-central-1" if parsed_arn["region"] != "eu-central-1" else "us-east-1"
        different_region_topic = topic_arn.replace(parsed_arn["region"], different_region)
        different_region_topic_confirm_url = f"{service_url}/?Action=ConfirmSubscription&TopicArn={different_region_topic}&Token={token}"
        region_topic_confirm_subscribe_request = requests.get(different_region_topic_confirm_url)
        snapshot.match(
            "different-region-arn-confirm",
            _get_snapshot_requests_response(region_topic_confirm_subscribe_request),
        )
        # b