### 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_
"""
    Validate the message attribute name with the specification of AWS.
    The message attribute name can contain the following characters: A-Z, a-z, 0-9, underscore(_), hyphen(-), and period (.). The name must not start or end with a period, and it should not have successive periods.
    :param name: message attribute name
    :raises InvalidParameterValueException: if the name does not conform to the spec
    """
    if not sns_constants.MSG_ATTR_NAME_REGEX.match(name):
        
        if name[0] == ".":
            raise InvalidParameterValueException(
                "Invalid message attribute name starting with character '.' was found."
            )
        elif name[-1] == ".":
            raise InvalidParameterValueException(
                "Invalid message attribute name ending with character '.' was found."
            )
        for idx, char in enumerate(name):
            if char not in sns_constants.VALID_MSG_ATTR_NAME_CHARS:
                
                hex_char = "#x" + hex(ord(char)).upper()[2:]
                raise InvalidParameterValueException(
                    f"Invalid non-alphanumeric character '{hex_char}' was found in the message attribute name. Can only include alphanumeric characters, hyphens, underscores, or dots."
                )
            
            if char == "." and name[idx - 1] == ".":
                raise InvalidParameterValueException(
                    "Message attribute name can not have successive '.' character."
                )
def extract_tags(