Add Captcha to prevent/limit scraping

[BenjaminMichaelis]

Have it pop up on some pages after a certain amount of time/number of pages navigated through to be completed before being able to see more content

[BenjaminMichaelis]

fix

        // The JSON should also return a field "success" as true
        // https://docs.hcaptcha.com/#verify-the-user-response-server-side
        // TODO: Implement this properly!!
        response.Success = true;

in Register.cshtml.cs