### 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_
},
                Destination={"ToAddresses": [subscriber.get("Endpoint")]},
            )
            store_delivery_log(subscriber, True, message, message_id)
    else:
        LOG.warning('Unexpected protocol "%s" for SNS subscription' % subscriber["Protocol"])
def publish_message(topic_arn, req_data, headers, subscription_arn=None, skip_checks=False):
    sns_backend = SNSBackend.get()
    message = req_data["Message"][0]
    message_id = str(uuid.uuid4())
    if topic_arn and ":endpoint/" in topic_arn:
        
        cache = sns_backend.platform_endpoint_messages[topic_arn] = (
            sns_backend.platform_endpoint_messages.get(topic_arn) or []
        )
        cache.append(req_data)
    LOG.debug("Publishing message to TopicArn: %s | Message: %s" % (topic_arn, message))
    start_thread(
        lambda _: message_to_subscribers(
            message_id,
            message,
            topic_arn,
            req_data,
            headers,
            subscription_arn,
            skip_checks,
        )
    )
    return message_id
def do_delete_topic(topic_arn):