### 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_
snapshot.match("messages-no-filter-after-publish-ok-1", response_after_publish_no_filter)
        response_after_publish_filter = aws_client.sqs.receive_message(
            QueueUrl=queue_url_with_filter, VisibilityTimeout=0, WaitTimeSeconds=sqs_wait_time
        )
        # t
        snapshot.match("messages-with-filter-after-publish-filtered", response_after_publish_filter)
    @pytest.mark.aws_validated
    @pytest.mark.skip_snapshot_verify(
        paths=["$.invalid-token.Error.Message"]  # v
    )
    def test_sns_confirm_subscription_wrong_token(self, sns_create_topic, snapshot, aws_client):
        topic_arn = sns_create_topic()["TopicArn"]
        with pytest.raises(ClientError) as e:
            wrong_topic = topic_arn[:-1] + "i"
            aws_client.sns.confirm_subscription(
                TopicArn=wrong_topic,
                Token="51b2ff3edb475b7d91550e0ab6edf0c1de2a34e6ebaf6c2262a001bcb7e051c43aa00022ceecce70bd2a67b2042da8d8eb47fef7a4e4e942d23e7fa56146b9ee35da040b4b8af564cc4184a7391c834cb75d75c22981f776ad1ce8805e9bab29da2329985337bb8095627907b46c8577c8440556b6f86582a954758026f41fc62041c4b3f67b0f5921232b5dae5aaca1",
            )
        snapshot.match("topic-not-exists", e.value.response)
        with pytest.raises(ClientError) as e:
            aws_client.sns.confirm_subscription(TopicArn=topic_arn, Token="randomtoken")
        snapshot.match("invalid-token", e.value.response)
        with pytest.raises(ClientError) as e:
            aws_client.sns.confirm_subscription(
                TopicArn=topic_arn,
                Token="51b2ff3edb475b7d91550e0ab6edf0c1de2a34e6ebaf6c2262a001bcb7e051c43aa00022ceecce70bd2a67b2042da8d8eb47fef7a4e4e942d23e7fa56146b9ee35da040b4b8af564cc4184a7391c834cb75d75c22981f776ad1ce8805e9bab29da2329985337bb8095627907b46c8577c8440556b6f86582a954758026f41fc62041c4b3f67b0f5921232b5dae5aaca1",
            )
        snapshot.match("token-not-exists", e.value.response)
@pytest.mark.only_localstack
class TestSNSMultiAccounts: