ActivityPub: Add basic, read-only support for Outboxes, Notes, and Create/Announce Activities (#2197)

* Clean up collapsible components

* Expose user Outboxes and AS2 representations of statuses

* Save work thus far.

* Fix bad merge.

* Save my work

* Clean up pagination.

* First test working.

* Add tests.

* Add Forbidden error template.

* Revert yarn.lock changes.

* Fix code style deviations and use localized instead of hardcoded English text.

app/controllers/application_controller.rb

@@ -62,6 +62,13 @@ class ApplicationController < ActionController::Base
     end
   end
 
+  def forbidden
+    respond_to do |format|
+      format.any  { head 403 }
+      format.html { render 'errors/403', layout: 'error', status: 403 }
+    end
+  end
+
   def unprocessable_entity
     respond_to do |format|
       format.any  { head 422 }