The report form doesn't recognise subdomains with underscores

Reported on behalf of https://github.com/AdguardTeam/AdguardFilters/issues/169739.

The original report discovered `https://all_words.academic.ru/44625/%D0%BD%D0%B0%D0%BF%D1%91%D1%80%D1%81%D1%82%D0%BE%D1%87%D0%BD%D0%B8%D0%BA` as a legitimate real URL whose subdomain used an underscore, and I can confirm that the URL is indeed accessible as a real site.

So I looked into this myself and tested with a (fake) test subdomain with a larger and English screenshot, and can indeed confirm the error message too:

As such, it appears the URL textbar in the report form needs to be updated to support underscores.