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 -->
env = get_environment(env)
    if not role:
        role = get_iam_role(resource, env=env)
    return role_arn(role_name=role, account_id=get_account_id())
def get_iam_role(resource, env=None):
    env = get_environment(env)
    return 'role-%s' % resource
def dynamodb_table_arn(table_name, account_id=None, region_name=None):
    pattern = 'arn:aws:dynamodb:%s:%s:table/%s'
    return _resource_arn(table_name, pattern, account_id=account_id, region_name=region_name)
def dynamodb_stream_arn(table_name, latest_stream_label, account_id=None):
    account_id = get_account_id(account_id)
    return ('arn:aws:dynamodb:%s:%s:table/%s/stream/%s' %
        (get_region(), account_id, table_name, latest_stream_label))
def lambda_function_arn(function_name, account_id=None):
    pattern = 'arn:aws:lambda:.*:.*:(function|layer):.*'
    if re.match(pattern, function_name):
        return function_name
    if ':' in function_name:
        raise Exception('Lambda function name should not contain a colon ":"')
    account_id = get_account_id(account_id)
    pattern = re.sub(r'\([^\|]+\|.+\)', 'function', pattern)
    return pattern.replace('.*', '%s') % (get_region(), account_id, function_name)
def lambda_function_name(name_or_arn):
    if ':' not in name_or_arn:
        return name_or_arn
    parts = name_or_arn.split(':')
    
    return parts[6]
def state_machine_arn(name, account_id=None, region_name=None):