### 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_
@pytest.mark.aws_validated
    @pytest.mark.skip_snapshot_verify(
        paths=[
            "$.sub-filter-policy-rule-no-list.Error.Message",  # m
        ]
    )
    def test_sub_filter_policy_nested_property_constraints(
        self, sqs_create_queue, sns_create_topic, sns_create_s, snapshot, aws_client
    ):
        # h
        topic_arn = sns_create_topic()["TopicArn"]
        queue_url = sqs_create_queue()
        subscription = sns_create_s(topic_arn=topic_arn, queue_url=queue_url)
        subscription_arn = subscription["SubscriptionArn"]
        aws_client.sns.set_subscription_attributes(
            SubscriptionArn=subscription_arn,
            AttributeName="FilterPolicyScope",
            AttributeValue="MessageBody",
        )
        nested_filter_policy = {
            "key_a": {
                "key_b": {"key_c": ["value_one", "value_two", "value_three", "value_four"]},
            },
            "key_d": {"key_e": ["value_one", "value_two", "value_three"]},
            "key_f": ["value_one", "value_two", "value_three"],
        }
        # T
        # n
        # 3 
        with pytest.raises(ClientError) as e: