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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LOG.debug('Lambda archive content:\n%s' % file_list)
                raise ClientError(error_response(
                    'Unable to find handler script in Lambda archive. %s' % config_debug,
                    400, error_type='ValidationError'))
        if runtime.startswith('python') and not use_docker():
            try:
                
                ensure_readable(main_file)
                zip_file_content = load_file(main_file, mode='rb')
                
                lambda_handler = exec_lambda_code(
                    zip_file_content,
                    handler_function=handler_function,
                    lambda_cwd=lambda_cwd,
                    lambda_env=lambda_environment)
            except Exception as e:
                raise ClientError('Unable to get handler function from lambda code.', e)
    add_function_mapping(lambda_name, lambda_handler, lambda_cwd)
    return {'FunctionName': lambda_name}
def do_list_functions():
    funcs = []
    for f_arn, func in arn_to_lambda.items():
        if type(func) != LambdaFunction:
            continue
        func_name = f_arn.split(':function:')[-1]
        arn = func_arn(func_name)
        func_details = arn_to_lambda.get(arn)
        funcs.append(format_func_details(func_details))
    return funcs
def format_func_details(func_details, version=None, always_add_version=False):