[Feature Request] Add support for multiple sitemaps

Created by: NickStees

What is the current behavior? I don't believe the crawler is handling sitemaps broken out into multiple sitemaps. This is common in large sites since sitemaps are limited to 50k urls. See Simplify multiple sitemap management

Good example is NASA https://www.nasa.gov/sitemap.xml

What is the expected behavior? Successfully crawl large sites via sitemap(s)

What is the motivation / use case for changing the behavior? Large enterprise sites not being crawled via sitemap