FEATURE: Introduce site settings which require confirmation (#27315)

Many site settings can be distructive or have huge side-effects
for a site that the admin may not be aware of when changing it.

This commit introduces a `requires_confirmation` attribute that
can be added to any site setting. When it is true, a confirmation
dialog will open if that setting is changed in the admin UI,
optionally with a custom message that is defined in client.en.yml.

If the admin does not confirm, we reset the setting to its previous
clean value and do not save the new value.

lib/tasks/javascript.rake

@@ -166,6 +166,8 @@ task "javascript:update_constants" => :environment do
     export const TOPIC_VISIBILITY_REASONS = #{Topic.visibility_reasons.to_json};
 
     export const SYSTEM_FLAG_IDS = #{PostActionType.types.to_json}
+
+    export const SITE_SETTING_REQUIRES_CONFIRMATION_TYPES = #{SiteSettings::TypeSupervisor::REQUIRES_CONFIRMATION_TYPES.to_json}
   JS
 
   pretty_notifications = Notification.types.map { |n| "  #{n[0]}: #{n[1]}," }.join("\n")