Add support for Yandex captcha

[crazy4cars69]

Add support for 3rd party Yandex SmartCaptcha. Docs: https://yandex.cloud/en-ru/docs/smartcaptcha/

[RealAngeleno]

Right on. Attempted to do this earlier, but didn't since I couldn't get a yandex account working and it felt low-priority. I'll put it on the list of stuff to do, and it can easily be added (e.g. 5.2.1).