### 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_
create_topic = sns_create_topic(
            Name="topictest.fifo",
            Attributes={
                "DisplayName": "TestTopic",
                "SignatureVersion": "2",
                "FifoTopic": "true",
            },
        )
        topic_arn = create_topic["TopicArn"]
        get_attrs_resp = aws_client.sns.get_topic_attributes(
            TopicArn=topic_arn,
        )
        snapshot.match("get-topic-attrs", get_attrs_resp)
        with pytest.raises(ClientError) as e:
            wrong_topic_arn = f"{topic_arn[:-8]}{short_uid()}"
            aws_client.sns.get_topic_attributes(TopicArn=wrong_topic_arn)
        snapshot.match("get-attrs-nonexistent-topic", e.value.response)
    @pytest.mark.aws_validated
    @pytest.mark.skip_snapshot_verify(paths=["$..Attributes.SubscriptionPrincipal"])
    def test_create_subscriptions_with_attributes(