### 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_
{"Id": "1", "Message": "Messages with the same ID"} for i in range(2)
                ],
            )
        snapshot.match("same-msg-id", e.value.response)
        with pytest.raises(ClientError) as e:
            aws_client.sns.publish_batch(
                TopicArn=topic_arn,
                BatchRequestEntries=[
                    {
                        "Id": "1",
                        "Message": "Test message without MessageDeduplicationId",
                        "MessageGroupId": "msg1",
                    }
                ],
            )
        snapshot.match("no-dedup-id", e.value.response)
        with pytest.raises(ClientError) as e:
            aws_client.sns.publish_batch(
                TopicArn=topic_arn,
                BatchRequestEntries=[
                    {
                        "Id": "1",
                        "Message": json.dumps({"sqs": "test sqs"}),
                        "MessageStructure": "json",
                    }
                ],
            )
        snapshot.match("no-default-key-json", e.value.response)
    @pytest.mark.aws_validated
    def test_subscribe_to_sqs_with_queue_url(