**Overview**

In AWS it is possible to trigger step functions through an API Gateway integration, see https://docs.aws.amazon.com/step-functions/latest/dg/tutorial-api-gateway.html

Similar integrations already occur within localstack, however the step function URIs are notably missing. See lines 66-88 of https://github.com/localstack/localstack/blob/master/localstack/services/apigateway/apigateway_listener.py



┆Issue is synchronized with this [Jira Bug](https://localstack.atlassian.net/browse/LOC-107) by [Unito](https://www.unito.io/learn-more)

result = GATEWAY_RESPONSES.get(api_id, [])
    base_path = '/restapis/%s/gatewayresponses' % api_id
    href = 'http://docs.aws.amazon.com/apigateway/latest/developerguide/restapi-gatewayresponse-{rel}.html'
    def item(i):
        i['_links'] = {
            'self': {
                'href': '%s/%s' % (base_path, i['responseType'])
            },
            'gatewayresponse:put': {
                'href': '%s/{response_type}' % base_path,
                'templated': True
            },
            'gatewayresponse:update': {
                'href': '%s/%s' % (base_path, i['responseType'])
            }
        }
        i['responseParameters'] = i.get('responseParameters', {})
        i['responseTemplates'] = i.get('responseTemplates', {})
        return i
    result = {
        '_links': {