CertSubjectName extracts one name that identifies the certificate.

ExtractAffectedDomains: extract the affected domain, given a list of domain name (common name + SANs).

IsValidDomain: check if this domain is a valid domain.

ParseDomainName: get the parent domain until E2LD, return a list of domains(remove the www.

SplitE2LD: return the E2LD and the rest of the domain names.

ErrInvalidDomainName: thrown when the domain name is not valid.