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 -->
try:
            if attribute_name == 'StreamArn':
                streams = aws_stack.connect_to_service('dynamodbstreams').list_streams(TableName=self.name)['Streams']
                return streams[0]['StreamArn'] if streams else None
            return DynamoDB_Table_get_cfn_attribute_orig(self, attribute_name)
        except Exception as e:
            LOG.warning('Unable to get attribute "%s" from resource %s: %s' % (attribute_name, type(self), e))
            raise
    DynamoDB_Table_get_cfn_attribute_orig = dynamodb_models.Table.get_cfn_attribute
    dynamodb_models.Table.get_cfn_attribute = DynamoDB_Table_get_cfn_attribute
    
    def IAM_Role_get_cfn_attribute(self, attribute_name):
        try:
            return IAM_Role_get_cfn_attribute_orig(self, attribute_name)
        except Exception:
            if attribute_name == 'Arn':
                return aws_stack.role_arn(self.name)
            raise
    IAM_Role_get_cfn_attribute_orig = iam_models.Role.get_cfn_attribute
    iam_models.Role.get_cfn_attribute = IAM_Role_get_cfn_attribute
    
    @classmethod
    def Lambda_create_from_cloudformation_json(cls, resource_name, cloudformation_json, region_name):
        resource_name = cloudformation_json.get('Properties', {}).get('FunctionName') or resource_name
        return Lambda_create_from_cloudformation_json_orig(resource_name, cloudformation_json, region_name)
    Lambda_create_from_cloudformation_json_orig = lambda_models.LambdaFunction.create_from_cloudformation_json
    lambda_models.LambdaFunction.create_from_cloudformation_json = Lambda_create_from_cloudformation_json
    
    @classmethod
    def Lambda_update_from_cloudformation_json(cls,