Implement `strategy` for `SitemapRequestList` URLs

[janbuchar]

• Add a strategy option analogous to enqueueLinks (defaults to same domain)
  • under any reasonable circumstances, sitemaps should never link outside of their domain, but we will provide an escape hatch
  • a warning should be printed for sitemap URLs that don't match the strategy

[janbuchar]

• See fix: Filter sitemap-derived URLs by enqueue strategy crawlee-python#1864