### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

When you publish a message to SNS without a *body* (e.g. only attributes) it succeeds.

### Expected Behavior

Trying to publish a message without a *body* should fail (at least it does when trying to do this in AWS)

### How are you starting LocalStack?

Custom (please describe below)

### Steps To Reproduce

#### How are you starting localstack (e.g., `bin/localstack` command, arguments, or `docker-compose.yml`)

using Java testcontainers...

#### Client commands (e.g., AWS SDK code snippet, or sequence of "awslocal" commands)

```bash
#!/bin/sh
 
queue_arn=$(awslocal sqs create-queue --queue-name $QUEUE_NAME --output text)
echo "Queue ARN: $queue_arn"

topic_arn=$(awslocal sns create-topic --name $TOPIC_NAME --output text)
echo "Topic ARN: $topic_arn"

subscription_arn=$(awslocal sns subscribe \
    --attributes RawMessageDelivery=true \
    --topic-arn "$topic_arn" \
    --protocol sqs \
    --notification-endpoint "$queue_arn" \
    --output text)
echo "Subscription ARN: $subscription_arn" 
```


### Environment

```markdown
- OS: OSX 11.5.2
- LocalStack: 0.13.0
- Docker Desktop: v20.10.8
```


### Anything else?

_No response_
response = Response()
    response._content = """<ErrorResponse xmlns="http://sns.amazonaws.com/doc/2010-03-31/"><Error>
        <Type>Sender</Type>
        <Code>{code_string}</Code>
        <Message>{message}</Message>
        </Error><RequestId>{req_id}</RequestId>
        </ErrorResponse>""".format(
        message=message, code_string=code_string, req_id=short_uid()
    )
    response.status_code = code
    return response
def create_sns_message_body(subscriber, req_data, message_id=None):
    message = req_data["Message"][0]
    protocol = subscriber["Protocol"]
    if six.PY2 and type(message).__name__ == "unicode":
        
        message = message.encode("raw-unicode-escape")
    if req_data.get("MessageStructure") == ["json"]:
        message = json.loads(message)
        try:
            message = message.get(protocol, message["default"])
        except KeyError:
            raise Exception("Unable to find 'default' key in message payload")
    if is_raw_message_delivery(subscriber):
        return message
    data = {
        "Type": req_data.get("Type", ["Notification"])[0],
        "MessageId": message_id,
        "TopicArn": subscriber["TopicArn"],
        "Message": message,