feat: whois reconcile loop for tlds not in rdap

[zachsmith1]

This pull request adds WHOIS-based domain registration support as a fallback when RDAP registration information is unavailable or incomplete. It introduces new logic to discover the authoritative WHOIS server using IANA bootstrap, follows registry and registrar referrals, and parses WHOIS responses to populate domain registration details. The changes also include new helper functions for WHOIS parsing and comprehensive tests for the fallback and referral logic.

Domain registration protocol selection and fallback:

• Updated DomainReconciler to select RDAP as the primary registration protocol and fall back to WHOIS if RDAP bootstrap reports no match, RDAP response is nil, or RDAP object is missing. The registration mapping now uses WHOIS parsing when needed.

WHOIS support and parsing:

• Added a new dependency on github.com/domainr/whois and implemented the whoisFetchAtHost helper for performing WHOIS queries at specific hosts.
• Implemented fetchRegistrationWhois, which discovers the authoritative WHOIS server via IANA, follows registry and registrar referrals, and parses WHOIS responses to extract registration, registrar, abuse contact, DNSSEC, statuses, and contact information.
• Added helper functions findWhoisValue and parseTimeFlex for robust WHOIS field extraction and flexible date parsing.

Nameserver population logic:

• Modified nameserver assignment to use RDAP nameservers when available, or resolve via DNS when using WHOIS or when RDAP data is missing. This ensures correct NS population regardless of the protocol used.
  Controller and dependency wiring:

• Added the whoisFetch function field to DomainReconciler and wired it during controller setup for dependency injection and testing.

Testing and validation:

• Added comprehensive tests for WHOIS bootstrap, registry and registrar referrals, and WHOIS-based registration mapping, ensuring correct extraction of all relevant domain registration fields.

[joshlreese]

Looks good. Left a couple non-blocking questions.