### 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_
self, context: RequestContext, resource_arn: AmazonResourceName, tags: TagList
    ) -> TagResourceResponse:
        
        
        unique_tag_keys = {tag["Key"] for tag in tags}
        if len(unique_tag_keys) < len(tags):
            raise InvalidParameterException("Invalid parameter: Duplicated keys are not allowed.")
        call_moto(context)
        store = self.get_store(context.account_id, context.region)
        existing_tags = store.sns_tags.get(resource_arn, [])
        def existing_tag_index(_item):
            for idx, tag in enumerate(existing_tags):
                if _item["Key"] == tag["Key"]:
                    return idx
            return None
        for item in tags:
            existing_index = existing_tag_index(item)
            if existing_index is None:
                existing_tags.append(item)
            else:
                existing_tags[existing_index] = item
        store.sns_tags[resource_arn] = existing_tags
        return TagResourceResponse()
    def delete_topic(self, context: RequestContext, topic_arn: topicARN) -> None: