FEATURE: Add setting to always confirm old email (#18417)

By default, only staff members have to confirm their old email when
changing it. This commit adds a site setting that when enabled will
always ask the user to confirm old email.

config/locales/server.en.yml

@@ -2044,6 +2044,7 @@ en:
     raw_email_max_length: "How many characters should be stored for incoming email."
     raw_rejected_email_max_length: "How many characters should be stored for rejected incoming email."
     delete_rejected_email_after_days: "Delete rejected emails older than (n) days."
+    require_change_email_confirmation: "Require non-staff users to confirm their old email address before changing it. Does not apply to staff users, they always need to confirm their old email address."
 
     manual_polling_enabled: "Push emails using the API for email replies."
     pop3_polling_enabled: "Poll via POP3 for email replies."

config/site_settings.yml

@@ -1291,6 +1291,7 @@ email:
   max_participant_names:
     default: 10
     hidden: true
+  require_change_email_confirmation: false
 
 files:
   max_image_size_kb: