Feature/sync Enable hcaptcha on login (#1469)

* Share globalSettings hcaptcha public key with clients

* Require captcha valid only prior to two factor

users with two factor will have already solved captcha is necessary.
Users without two factor will have`TwoFactorVerified` set to false

* Do not require CaptchaResponse on two-factor requests

* Add option to always require captcha for testing purposes

* Allow for self-hosted instances if they want to use it

* Move refresh suggestion to correct error

* Expect lifetime in helper method

* Add captcha bypass token to successful captcha validations

* Remove twofactorValidated

* PR Feedback

src/Core/Settings/GlobalSettings.cs

@@ -473,6 +473,7 @@ namespace Bit.Core.Settings
 
         public class CaptchaSettings
         {
+            public bool RequireCaptcha { get; set; } = false;
             public string HCaptchaSecretKey { get; set; }
             public string HCaptchaSiteKey { get; set; }
         }