### 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()
    for topic_arn, existing_subs in sns_backend.sns_subscriptions.items():
        sns_backend.sns_subscriptions[topic_arn] = [
            sub for sub in existing_subs if sub["SubscriptionArn"] != subscription_arn
        ]
def _get_tags(topic_arn):
    sns_backend = SNSBackend.get()
    if topic_arn not in sns_backend.sns_tags:
        sns_backend.sns_tags[topic_arn] = []
    return sns_backend.sns_tags[topic_arn]
def do_list_tags_for_resource(topic_arn):
    return _get_tags(topic_arn)
def do_tag_resource(topic_arn, tags):
    sns_backend = SNSBackend.get()
    existing_tags = sns_backend.sns_tags.get(topic_arn, [])
    tags = [tag for idx, tag in enumerate(tags) if tag not in tags[:idx]]
    def existing_tag_index(item):
        for idx, tag in enumerate(existing_tags):
            if item["Key"] == tag["Key"]:
                return idx
        return None
    for item in tags:
        existing_index = existing_tag_index(item)
        if existing_index is None:
            existing_tags.append(item)
        else:
            existing_tags[existing_index] = item
    sns_backend.sns_tags[topic_arn] = existing_tags
def do_untag_resource(topic_arn, tag_keys):