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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for response_config in response_configs:
            
            client.put_integration_response(
                restApiId=api_id,
                resourceId=resource_id,
                httpMethod=method['httpMethod'],
                statusCode=response_config['code'],
                responseTemplates=response_config['res_templates'],
                selectionPattern=response_config['pattern']
            )
            
            client.put_method_response(
                restApiId=api_id,
                resourceId=resource_id,
                httpMethod=method['httpMethod'],
                statusCode=response_config['code']
            )
def apigateway_invocations_arn(lambda_uri):
    return ('arn:aws:apigateway:%s:lambda:path/2015-03-31/functions/%s/invocations' %
        (get_region(), lambda_uri))
def get_elasticsearch_endpoint(domain=None, region_name=None):
    env = get_environment(region_name=region_name)
    if is_local_env(env):
        return os.environ['TEST_ELASTICSEARCH_URL']
    
    es_client = connect_to_service(service_name='es', region_name=env.region)
    info = es_client.describe_elasticsearch_domain(DomainName=domain)
    endpoint = 'https://%s' % info['DomainStatus']['Endpoint']
    return endpoint
def connect_elasticsearch(endpoint=None, domain=None, region_name=None, env=None):