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 -->
if resources is None:
        apigateway = connect_to_service(service_name='apigateway')
        resources = apigateway.get_resources(restApiId=api_id, limit=100)
    if not isinstance(path, list):
        path = path.split('/')
    if not path:
        return parent
    for resource in resources:
        if resource['pathPart'] == path[0] and (not parent or parent['id'] == resource['parentId']):
            return get_apigateway_resource_for_path(api_id, path[1:], parent=resource, resources=resources)
    return None
def get_apigateway_path_for_resource(api_id, resource_id, path_suffix='', resources=None, region_name=None):
    if resources is None:
        apigateway = connect_to_service(service_name='apigateway', region_name=region_name)
        resources = apigateway.get_resources(restApiId=api_id, limit=100)['items']
    target_resource = list(filter(lambda res: res['id'] == resource_id, resources))[0]
    path_part = target_resource.get('pathPart', '')
    if path_suffix:
        if path_part:
            path_suffix = '%s/%s' % (path_part, path_suffix)
    else:
        path_suffix = path_part
    parent_id = target_resource.get('parentId')
    if not parent_id:
        return '/%s' % path_suffix
    return get_apigateway_path_for_resource(api_id, parent_id,
        path_suffix=path_suffix, resources=resources, region_name=region_name)
def create_api_gateway(name, description=None, resources=None, stage_name=None,