### 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_
sns_backend = SNSBackend.get()
    sns_backend.sns_subscriptions.pop(topic_arn, None)
    sns_backend.sns_tags.pop(topic_arn, None)
def do_confirm_subscription(topic_arn, token):
    sns_backend = SNSBackend.get()
    for k, v in sns_backend.subscription_status.items():
        if v["Token"] == token and v["TopicArn"] == topic_arn:
            v["Status"] = "Subscribed"
def do_subscribe(topic_arn, endpoint, protocol, subscription_arn, attributes, filter_policy=None):
    sns_backend = SNSBackend.get()
    topic_subs = sns_backend.sns_subscriptions[topic_arn] = (
        sns_backend.sns_subscriptions.get(topic_arn) or []
    )
    
    
    for existing_topic_subscription in topic_subs:
        if existing_topic_subscription.get("Endpoint") == endpoint:
            return
    subscription = {
        
        "TopicArn": topic_arn,
        "Endpoint": endpoint,
        "Protocol": protocol,
        "SubscriptionArn": subscription_arn,
        "FilterPolicy": filter_policy,