2FA controller cleanup (#2296)

* Add spec coverage for settings/two_factor_auth area

* extract setup method for qr code

* Move otp required check to before action

* Merge method only used once

* Remove duplicate view

* Consolidate creation of @codes for backup

* Move settings/2fq#recovery_codes to settings/recovery_codes#create

* Rename settings/two_factor_auth#disable to #destroy

* Add coverage for the otp required path on 2fa#show

* Clean up the recovery codes list styles

* Move settings/two_factor_auth to settings/two_factor_authentication

* Reorganize the settings two factor auth area

Updated to use a flow like:

- settings/two_factor_authentication goes to a #show view which has a button
  either enable or disable 2fa on the account
- the disable button turns off the otp requirement for the user
- the enable button cycles the user secret and redirects to a confirmation page
- the confirmation page is a #new view which shows the QR code for user
- that page posts to #create which verifies the code, and creates the recovery
  codes
- that create action shares a view with a recovery codes controller which can be
  used separately to reset codes if needed

config/locales/bg.yml

@@ -139,7 +139,7 @@ bg:
     import: Импортиране
     preferences: Предпочитания
     settings: Настройки
-    two_factor_auth: Двустепенно удостоверяване
+    two_factor_authentication: Двустепенно удостоверяване
   statuses:
     open_in_web: Отвори в уеб
     over_character_limit: прехвърлен лимит от %{max} символа
@@ -155,7 +155,7 @@ bg:
   time:
     formats:
       default: "%d %b, %Y, %H:%M"
-  two_factor_auth:
+  two_factor_authentication:
     description_html: При активация на <strong>двустепенно удостоверяване</strong>, за да влезеш в приложението, ще трябва да използваш телефона си. През него ще се генерира код, който да въвеждаш при влизане.
     disable: Деактивирай
     enable: Активирай