[tests] Add Test Cases Ensuring Working of WHOIS storage and retrieval

[DragnEmperor]

Add unit and integration tests to ensure working of WHOIS-related logic. This includes:

• Testing fetch_whois_details task for correct parsing and saving of WHOIS data
• Verifying creation and update behavior of WHOISInfo model
• Ensuring trigger_whois_lookup is called only when last IP is public and has changed
• Adding tests for the periodic refresh task

Dependencies

• [feature] Add Whois model and basic functionality #1032
• [feature] Implement Celery task for WHOIS fetch based on device last IP #1033
• [enhancement] Make WhoIs feature configurable (enabled/disabled) #1037