[Feature] Support Cloudflare Turnstile or HCaptcha

[parasiteoflife]

Please add support for Cloudflare Turnstile and/or HCaptcha, they are more privacy friendly than Google's

[evereq]

1. Make sure it's possible to use HCaptcha IF relevant env vars are set. If they are not set, use other Captcha provider (e.g. one we already support - Google, as long as it's env vars are set) or make sure NO captcha is used if no env vars are set for any provider. So, first check env vars we have for Google and create similar for HCaptcha). Alternative approach would be to add env var CAPTCHA_TYPE and have values like google, hcaptcha, cloudflare etc. (I think that is even better approach as long as all captchas need same env vars with tokens etc)

2. For HCaptcha, see below:

• https://github.com/hCaptcha/react-hcaptcha
• https://github.com/vastus/node-hcaptcha
• https://github.com/neg4n/next-hcaptcha (Note: it's outdated, not sure how useful is it, maybe more like some reference only. Google for correct implementation of HCaptcha in NextJs APIs!)

3. For Cloudflare Turnstile there are a lot of blogs how to integrate, so Google for it :)

[evereq]

Implemented in #3550