Add option to set bulk subdomains for exclusion from AutoSSL for all accounts.

With 700+ accounts, I would like to see an option as part of the AutoSSL UI to select/specify certain subdomains (m., www., mail., etc.) that would be ignored/excluded for all AutoSSL accounts when requesting a certificate.

AutoSSL would not test these subdomains for valid resolution, and would not request them as part of the certificate for that account when running the AutoSSL check for that account, either individually or as part of the "check all accounts" AutoSSL run.