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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match = [v for (k, v) in res_obj['resourceMethods'].items()
                     if resource_props['HttpMethod'] in (v.get('httpMethod'), k)]
            return match or None
        elif resource_type == 'SQS::Queue':
            sqs_client = aws_stack.connect_to_service('sqs')
            queues = sqs_client.list_queues()
            result = list(filter(lambda item:
                
                item.endswith('/%s' % resource_id), queues.get('QueueUrls', [])))
            if not result:
                return None
            result = sqs_client.get_queue_attributes(QueueUrl=result[0], AttributeNames=['All'])['Attributes']
            result['Arn'] = result['QueueArn']
            return result
        elif resource_type == 'SNS::Topic':
            topics = aws_stack.connect_to_service('sns').list_topics()
            result = list(filter(lambda item: item['TopicArn'] == resource_id, topics.get('Topics', [])))
            return result[0] if result else None
        elif resource_type == 'S3::Bucket':
            bucket_name = resource_props.get('BucketName') or resource_id
            return aws_stack.connect_to_service('s3').get_bucket_location(Bucket=bucket_name)
        elif resource_type == 'Logs::LogGroup':
            
            raise Exception('ResourceNotFound')
        elif resource_type == 'Kinesis::Stream':
            stream_name = resolve_refs_recursively(stack_name, resource_props['Name'], resources)
            result = aws_stack.connect_to_service('kinesis').describe_stream(StreamName=stream_name)
            return result
        elif resource_type == 'StepFunctions::StateMachine':
            sm_name = resource_props.get('StateMachineName') or resource_id