### 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_
"""
        Base method for publishing the message. It is up to the child class to implement its way to publish the message
        :param context: the SnsPublishContext created by the caller, containing the necessary data to publish the
        message
        :param endpoint: the endpoint where the message should be published
        :return:
        """
        raise NotImplementedError
    def prepare_message(self, message_context: SnsMessage, endpoint: str) -> str:
        """
        Base method to format the message. It is up to the child class to implement it.
        :param message_context: the SnsMessage containing the message data
        :param endpoint: the endpoint where the message should be published
        :return: the formatted message
        """
        raise NotImplementedError
class LambdaTopicPublisher(TopicPublisher):
    """
    The Lambda publisher is responsible for invoking a subscribed lambda function to process the SNS message using
    `Lambda.invoke` with the formatted message as Payload.
    See: https://docs.aws.amazon.com/lambda/latest/dg/with-sns.html
    """
    def _publish(self, context: SnsPublishContext, subscriber: SnsSubscription):
        try:
            region = extract_region_from_arn(subscriber["Endpoint"])
            lambda_client = connect_to(region_name=region).awslambda.request_metadata(
                source_arn=subscriber["TopicArn"], service_principal="sns"
            )
            event = self.prepare_message(context.message, subscriber)