### 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_
return sns_backends[account_id][region_name]
    @staticmethod
    def _get_topic(arn: str, context: RequestContext) -> Topic:
        arn_data = parse_and_validate_topic_arn(arn)
        try:
            return sns_backends[arn_data["account"]][context.region].topics[arn]
        except KeyError:
            raise NotFoundException("Topic does not exist")
    def get_topic_attributes(
        self, context: RequestContext, topic_arn: topicARN
    ) -> GetTopicAttributesResponse:
        moto_response: GetTopicAttributesResponse = call_moto(context)
        
        
        
        
        
        
        
        moto_topic_model = self._get_topic(topic_arn, context)
        for attr in vars(moto_topic_model):
            if "success_feedback" in attr:
                key = camelcase_to_pascal(underscores_to_camelcase(attr))
                moto_response["Attributes"][key] = getattr(moto_topic_model, attr)
            elif attr == "signature_version":
                moto_response["Attributes"]["SignatureVersion"] = moto_topic_model.signature_version
        return moto_response
    def publish_batch(