### 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_
subscriptions = ctx.store.get_topic_subscriptions(topic_arn)
        for subscriber in subscriptions:
            protocol = subscriber["Protocol"]
            notifier = self.batch_topic_notifiers.get(protocol)
            
            if notifier:
                subscriber_ctx = ctx
                messages_amount_before_filtering = len(ctx.messages)
                filtered_messages = [
                    message
                    for message in ctx.messages
                    if self._should_publish(
                        ctx.store.subscription_filter_policy, message, subscriber
                    )
                ]
                if not filtered_messages:
                    LOG.debug(
                        "No messages match filter policy, not publishing batch from topic '%s' to subscription '%s'",
                        topic_arn,
                        subscriber["SubscriptionArn"],
                    )