### 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_
"""
    The SMS publisher is responsible for publishing the SNS message directly to a phone number.
    This is not directly implemented yet in LocalStack, we only save the message.
    """
    def _publish(self, context: SnsPublishContext, endpoint: str):
        event = self.prepare_message(context.message, endpoint)
        context.store.sms_messages.append(event)
        LOG.info(
            "Delivering SMS message to %s: %s",
            event["endpoint"],
            event["message_content"],
        )
        
        
    def prepare_message(self, message_context: SnsMessage, endpoint: str) -> dict:
        return {
            "topic_arn": None,
            "endpoint": endpoint,
            "message_content": message_context.message_content("sms"),
        }
class ApplicationEndpointPublisher(EndpointPublisher):