### 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 application publisher is responsible for publishing the SNS message to a subscribed SNS application endpoint.
    The SNS application endpoint represents a mobile app and device.
    The application endpoint can be of different types, represented in `SnsApplicationPlatforms`.
    This is not directly implemented yet in LocalStack, we save the message to be retrieved later from an internal
    endpoint.
    The `LEGACY_SNS_GCM_PUBLISHING` flag allows direct publishing to the GCM platform, with some caveats:
    - It always publishes if the platform is GCM, and raises an exception if the credentials are wrong.
    - the Platform Application should be validated before and not while publishing
    See https://docs.aws.amazon.com/sns/latest/dg/sns-mobile-application-as-subscriber.html
    """
    def _publish(self, context: SnsPublishContext, subscriber: SnsSubscription):
        endpoint_arn = subscriber["Endpoint"]
        message = self.prepare_message(context.message, subscriber)
        cache = context.store.platform_endpoint_messages.setdefault(endpoint_arn, [])
        cache.append(message)
        if (
            config.LEGACY_SNS_GCM_PUBLISHING
            and get_platform_type_from_endpoint_arn(endpoint_arn) == "GCM"
        ):
            self._legacy_publish_to_gcm(context, endpoint_arn)
        
        
        store_delivery_log(context.message, subscriber, success=True)
    def prepare_message(