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 -->
from elasticsearch import Elasticsearch, RequestsHttpConnection
    from requests_aws4auth import AWS4Auth
    env = get_environment(env, region_name=region_name)
    verify_certs = False
    use_ssl = False
    if not endpoint and is_local_env(env):
        endpoint = os.environ['TEST_ELASTICSEARCH_URL']
    if not endpoint and not is_local_env(env) and domain:
        endpoint = get_elasticsearch_endpoint(domain=domain, region_name=env.region)
    
    if 'https://' in endpoint:
        use_ssl = True
        if not is_local_env(env):
            verify_certs = True
    if CUSTOM_BOTO3_SESSION or (ENV_ACCESS_KEY in os.environ and ENV_SECRET_KEY in os.environ):
        access_key = os.environ.get(ENV_ACCESS_KEY)
        secret_key = os.environ.get(ENV_SECRET_KEY)
        session_token = os.environ.get(ENV_SESSION_TOKEN)
        if CUSTOM_BOTO3_SESSION:
            credentials = CUSTOM_BOTO3_SESSION.get_credentials()
            access_key = credentials.access_key
            secret_key = credentials.secret_key
            session_token = credentials.token
        awsauth = AWS4Auth(access_key, secret_key, env.region, 'es', session_token=session_token)
        connection_class = RequestsHttpConnection
        return Elasticsearch(hosts=[endpoint], verify_certs=verify_certs, use_ssl=use_ssl,
                             connection_class=connection_class, http_auth=awsauth)
    return Elasticsearch(hosts=[endpoint], verify_certs=verify_certs, use_ssl=use_ssl)
def create_kinesis_stream(stream_name, shards=1, env=None, delete=False):