Hi

I have issues creating sns subscriptions through Cloudformation. If I attempt to include a `AWS::SNS::Subscription` resource in a Cloudformation template and run `create-stack` then I get a 500 Internal Server error. The full template:

```
AWSTemplateFormatVersion: '2010-09-09'
Description: 'Test'
Resources:
  MySnsTopic:
    Type: AWS::SNS::Topic
    Properties:
      TopicName: MySnsTopic
  MySnsTopicSubscription:
    Type: AWS::SNS::Subscription
    Properties:
      Protocol: sqs
      TopicArn: !Ref MySnsTopic
      Endpoint: !GetAtt
        - MySqsQueue
        - QueueArn
  MySqsQueue:
    Type: AWS::SQS::Queue
    Properties:
      QueueName: MySqsQueue
```

If I replace the references with hard-coded arns like this:

```
TopicArn: arn:aws:sns:eu-west-2:123456789012:MySnsTopic
Endpoint: arn:aws:sqs:elasticmq:000000000000:MySqsQueue
```

Then I get no errors but I get a warning:

`No moto Cloudformation support for AWS::SNS::Subscription`.

I can get around this issue by creating the subscription when creating the topic but the issue there is that I cannot add any attributes and in my case I need `RawMessageDelivery` set to true. So my questions are:

1. Is there no support to create `AWS::SNS::Subscription` resources through Cloudformation or am I doing something wrong?
2. If support is not there can I request it as a new feature?
3. Any suggestions on how I can work around this? I know I could do this through a script at startup but would like to not have any additional script steps other than deploying the Cloudformation stack.

<!-- Love localstack? Please consider supporting our collective:
👉  https://opencollective.com/localstack/donate -->
self._stdout = self.LogStreamIO()
        self._stderr = self.LogStreamIO()
    def __enter__(self):
        
        from werkzeug.local import LocalProxy
        ident = self._ident()
        if ident not in self.CONTEXTS_BY_THREAD:
            self.CONTEXTS_BY_THREAD[ident] = self
            self._set(LocalProxy(self._proxy(sys.stdout, 'stdout')),
                      LocalProxy(self._proxy(sys.stderr, 'stderr')),
                      LocalProxy(self._proxy(sys.__stdout__, 'stdout')),
                      LocalProxy(self._proxy(sys.__stderr__, 'stderr')))
        return self
    def __exit__(self, type, value, traceback):
        ident = self._ident()
        removed = self.CONTEXTS_BY_THREAD.pop(ident, None)
        if not self.CONTEXTS_BY_THREAD:
            
            self._set(self.orig_stdout, self.orig_stderr, self.orig___stdout, self.orig___stderr)
        
        removed._stdout.flush()
        removed._stderr.flush()
        out = removed._stdout.getvalue()
        err = removed._stderr.getvalue()
        
        removed._stdout.close()
        removed._stderr.close()
        removed._stdout = out
        removed._stderr = err
    def _set(self, out, err, __out, __err):