### 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_
):
                        individual_ctx = SnsPublishContext(
                            message=message, store=ctx.store, request_headers=ctx.request_headers
                        )
                        LOG.debug(
                            "Topic '%s' batch publishing '%s' to subscribed '%s' with protocol '%s' (subscription '%s')",
                            topic_arn,
                            individual_ctx.message.message_id,
                            subscriber.get("Endpoint"),
                            subscriber["Protocol"],
                            subscriber["SubscriptionArn"],
                        )
                        self.executor.submit(
                            notifier.publish, context=individual_ctx, subscriber=subscriber
                        )
    def publish_to_phone_number(self, ctx: SnsPublishContext, phone_number: str) -> None:
        LOG.debug(
            "Publishing '%s' to phone number '%s' with protocol 'sms'",
            ctx.message.message_id,
            phone_number,
        )
        self.executor.submit(self.sms_notifier.publish, context=ctx, endpoint=phone_number)
    def publish_to_application_endpoint(self, ctx: SnsPublishContext, endpoint_arn: str) -> None:
        LOG.debug(
            "Publishing '%s' to application endpoint '%s'",
            ctx.message.message_id,
            endpoint_arn,
        )
        self.executor.submit(self.application_notifier.publish, context=ctx, endpoint=endpoint_arn)
    def publish_to_topic_subscriber(