Add password challenge to 2FA settings, e-mail notifications (#11878)

Fix #3961

config/locales/devise.en.yml

@@ -46,6 +46,18 @@ en:
         extra: If you didn't request this, please ignore this email. Your password won't change until you access the link above and create a new one.
         subject: 'Mastodon: Reset password instructions'
         title: Password reset
+      two_factor_disabled:
+        explanation: Two-factor authentication for your account has been disabled. Login is now possible using only e-mail address and password.
+        subject: 'Mastodon: Two-factor authentication disabled'
+        title: 2FA disabled
+      two_factor_enabled:
+        explanation: Two-factor authentication has been enabled for your account. A token generated by the paired TOTP app will be required for login.
+        subject: 'Mastodon: Two-factor authentication enabled'
+        title: 2FA enabled
+      two_factor_recovery_codes_changed:
+        explanation: The previous recovery codes have been invalidated and new ones generated.
+        subject: 'Mastodon: Two-factor recovery codes re-generated'
+        title: 2FA recovery codes changed
       unlock_instructions:
         subject: 'Mastodon: Unlock instructions'
     omniauth_callbacks:

config/locales/en.yml

@@ -621,6 +621,11 @@ en:
       return: Show the user's profile
       web: Go to web
     title: Follow %{acct}
+  challenge:
+    confirm: Continue
+    hint_html: "<strong>Tip:</strong> We won't ask you for your password again for the next hour."
+    invalid_password: Invalid password
+    prompt: Confirm password to continue
   datetime:
     distance_in_words:
       about_x_hours: "%{count}h"

config/locales/simple_form.en.yml

@@ -43,6 +43,8 @@ en:
         domain: This domain will be able to fetch data from this server and incoming data from it will be processed and stored
       featured_tag:
         name: 'You might want to use one of these:'
+      form_challenge:
+        current_password: You are entering a secure area
       imports:
         data: CSV file exported from another Mastodon server
       invite_request: