Change public accounts pages to mount the web UI (#19319)

* Change public accounts pages to mount the web UI

* Fix handling of remote usernames in routes

- When logged in, serve web app
- When logged out, redirect to permalink
- Fix `app-body` class not being set sometimes due to name conflict

* Fix missing `multiColumn` prop

* Fix failing test

* Use `discoverable` attribute to control indexing directives

* Fix `<ColumnLoading />` not using `multiColumn`

* Add `noindex` to accounts in REST API

* Change noindex directive to not be rendered by default before a route is mounted

* Add loading indicator for detailed status in web UI

* Fix missing indicator appearing while account is loading in web UI

app/controllers/concerns/account_controller_concern.rb

@@ -3,13 +3,12 @@
 module AccountControllerConcern
   extend ActiveSupport::Concern
 
+  include WebAppControllerConcern
   include AccountOwnedConcern
 
   FOLLOW_PER_PAGE = 12
 
   included do
-    layout 'public'
-
     before_action :set_instance_presenter
     before_action :set_link_headers, if: -> { request.format.nil? || request.format == :html }
   end

app/controllers/concerns/web_app_controller_concern.rb

@@ -4,15 +4,24 @@ module WebAppControllerConcern
   extend ActiveSupport::Concern
 
   included do
-    before_action :set_body_classes
+    before_action :redirect_unauthenticated_to_permalinks!
+    before_action :set_app_body_class
     before_action :set_referrer_policy_header
   end
 
-  def set_body_classes
+  def set_app_body_class
     @body_classes = 'app-body'
   end
 
   def set_referrer_policy_header
     response.headers['Referrer-Policy'] = 'origin'
   end
+
+  def redirect_unauthenticated_to_permalinks!
+    return if user_signed_in?
+
+    redirect_path = PermalinkRedirector.new(request.path).redirect_path
+
+    redirect_to(redirect_path) if redirect_path.present?
+  end
 end