Automatically scan both www.example.com and example.com

The sites.yaml could be simplified for top-level sites that repeat their www. subdomain variants. Prior it should be verified that all top-level sites are expected to also respond on the www. subdomain.

Identifying top-level sites in sites.yaml can be done by checking if a given domain fits the eTLD+1 schema, see https://developer.mozilla.org/en-US/docs/Glossary/eTLD. Our tooling can fetch the public suffix list directly from https://publicsuffix.org/list/public_suffix_list.dat.