### 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_
topic_arn = sns_create_topic()["TopicArn"]
        with pytest.raises(ClientError) as exc:
            aws_client.sns.tag_resource(
                ResourceArn=topic_arn,
                Tags=[
                    {"Key": "k1", "Value": "v1"},
                    {"Key": "k2", "Value": "v2"},
                    {"Key": "k2", "Value": "v2"},
                ],
            )
        snapshot.match("duplicate-key-error", exc.value.response)
        aws_client.sns.tag_resource(
            ResourceArn=topic_arn,
            Tags=[
                {"Key": "k1", "Value": "v1"},
                {"Key": "k2", "Value": "v2"},
            ],
        )
        tags = aws_client.sns.list_tags_for_resource(ResourceArn=topic_arn)
        # c
        tags["Tags"].sort(key=itemgetter("Key"))
        snapshot.match("list-created-tags", tags)
        aws_client.sns.untag_resource(ResourceArn=topic_arn, TagKeys=["k1"])
        tags = aws_client.sns.list_tags_for_resource(ResourceArn=topic_arn)
        snapshot.match("list-after-delete-tags", tags)
        # t
        aws_client.sns.tag_resource(ResourceArn=topic_arn, Tags=[{"Key": "k2", "Value": "v2b"}])
        tags = aws_client.sns.list_tags_for_resource(ResourceArn=topic_arn)