### 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 endpoint_arn.rsplit("/", maxsplit=3)[1]  
def get_application_platform_arn_from_endpoint_arn(endpoint_arn: str) -> str:
    """
    Retrieve the application_platform information from the endpoint_arn to build the application platform ARN
    The format of the endpoint is:
    `arn:aws:sns:{region}:{account_id}:endpoint/{platform_type}/{application_name}/{endpoint_id}`
    :param endpoint_arn: str
    :return: application_platform_arn: str
    """
    parsed_arn = parse_arn(endpoint_arn)
    _, platform_type, app_name, _ = parsed_arn["resource"].split("/")
    base_arn = f'arn:aws:sns:{parsed_arn["region"]}:{parsed_arn["account"]}'
    return f"{base_arn}:app/{platform_type}/{app_name}"
def get_attributes_for_application_endpoint(endpoint_arn: str) -> Tuple[Dict, Dict]:
    """
    Retrieve the attributes necessary to send a message directly to the platform (credentials and token)
    :param endpoint_arn:
    :return:
    """
    sns_client = connect_to().sns
    
    endpoint_attributes = sns_client.get_endpoint_attributes(EndpointArn=endpoint_arn)
    app_platform_arn = get_application_platform_arn_from_endpoint_arn(endpoint_arn)
    app = sns_client.get_platform_application_attributes(PlatformApplicationArn=app_platform_arn)
    return app.get("Attributes", {}), endpoint_attributes.get("Attributes", {})
def send_message_to_gcm(