Find cities and regions available for monitoring in a market

Searches the locations that can be monitored inside one country, such as states, regions and cities, for the chosen search engines (a location must be supported by every engine selected). Without query it returns the country and the most common locations. With main_cities=true it returns only the market's main cities (United States, United Kingdom and Spain), which fills a project's location list quickly; other markets return none. Pass the returned code and name in locations to create_project or update_project.