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.

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return result[0] if result else None
        elif resource_type == 'ApiGateway::Resource':
            api_id = resource_props['RestApiId'] if resource else resource_id
            api_id = resolve_refs_recursively(stack_name, api_id, resources)
            parent_id = resolve_refs_recursively(stack_name, resource_props['ParentId'], resources)
            if not api_id or not parent_id:
                return None
            api_resources = aws_stack.connect_to_service('apigateway').get_resources(restApiId=api_id)['items']
            target_resource = list(filter(lambda res:
                res.get('parentId') == parent_id and res['pathPart'] == resource_props['PathPart'], api_resources))
            if not target_resource:
                return None
            path = aws_stack.get_apigateway_path_for_resource(api_id,
                target_resource[0]['id'], resources=api_resources)
            result = list(filter(lambda res: res['path'] == path, api_resources))
            return result[0] if result else None
        elif resource_type == 'ApiGateway::Deployment':
            api_id = resource_props['RestApiId'] if resource else resource_id
            api_id = resolve_refs_recursively(stack_name, api_id, resources)
            if not api_id:
                return None
            result = aws_stack.connect_to_service('apigateway').get_deployments(restApiId=api_id)['items']
            
            return result[0] if result else None
        elif resource_type == 'ApiGateway::Method':
            api_id = resolve_refs_recursively(stack_name, resource_props['RestApiId'], resources)
            res_id = resolve_refs_recursively(stack_name, resource_props['ResourceId'], resources)
            if not api_id or not res_id:
                return None
            res_obj = aws_stack.connect_to_service('apigateway').get_resource(restApiId=api_id, resourceId=res_id)