Hello,
I have tried to create a mock integration in api gateway from cloudformation.
Tested with latest (105b2dd7ba2c) docker-image.

We would like to be able to test our api-keys in api gateway but setting up ApiKeyRequired does not seem to work.

Using attached template.yml
Running:
aws cloudformation create-stack --stack-name api-gateway --template-body file://template.yml --endpoint-url=http://localhost:4566
aws apigateway get-rest-apis --endpoint-url=http://localhost:4566
aws apigateway get-resources --rest-api-id ${CREATED_REST_API_ID} --endpoint-url=http://localhost:4566

But the response here is apiKeyRequired = false
```
{
    "items": [
        {
            "id": "rootId",
            "path": "/"
        },
        {
            "id": "childId",
            "parentId": "rootId",
            "pathPart": "mock",
            "path": "/mock",
            "resourceMethods": {
                "POST": {
                    "httpMethod": "POST",
                    "authorizationType": "NONE",
                    "apiKeyRequired": false,
                    "methodIntegration": {
                        "type": "MOCK",
                        "requestParameters": {},
                        "requestTemplates": {
                            "application/json": "{\"statusCode\": $input.json('$.statusCode'), \"message\": $input.json('$.message')}"
                        },
                        "passthroughBehavior": "WHEN_NO_MATCH",
                        "cacheNamespace": "d30e4c73",
                        "cacheKeyParameters": []
                    }
                }
            }
        }
    ]
}
```
It is also possible to access the endpoint without providing an api key.
```
curl -v -H "Content-Type: application/json" http://localhost:4566/restapis/${CREATED_REST_API_ID}/LATEST/_user_request_/mock -d ' 
{"statusCode":200}
'
```

Expecting forbidden as when this template is run in AWS.

Regards,
Björn Bohlin
[template.zip](https://github.com/localstack/localstack/files/7097904/template.zip)

return "AWS::ApiGateway::Resource"
    def fetch_state(self, stack_name, resources):
        props = self.props
        api_id = props.get("RestApiId") or self.resource_id
        api_id = self.resolve_refs_recursively(stack_name, api_id, resources)
        parent_id = self.resolve_refs_recursively(stack_name, props.get("ParentId"), resources)
        if not api_id or not parent_id:
            return None
        api_resources = aws_stack.connect_to_service("apigateway").get_resources(restApiId=api_id)[
            "items"
        ]
        target_resource = list(
            filter(
                lambda res: res.get("parentId") == parent_id
                and res["pathPart"] == props["PathPart"],
                api_resources,
            )
        )
        if not target_resource:
            return None
        path = aws_stack.get_apigateway_path_for_resource(
            api_id, target_resource[0]["id"], resources=api_resources
        )
        result = list(filter(lambda res: res["path"] == path, api_resources))
        return result[0] if result else None
    @staticmethod
    def get_deploy_templates():