Merge pull request from GHSA-58x8-3qxw-6hm7

* Fix insufficient permission checking for public timeline endpoints

Note that this changes unauthenticated access failure code from 401 to 422

* Add more tests for public timelines

* Require user token in `/api/v1/statuses/:id/translate` and `/api/v1/scheduled_statuses`

app/controllers/api/v1/timelines/base_controller.rb

@@ -3,8 +3,14 @@
 class Api::V1::Timelines::BaseController < Api::BaseController
   after_action :insert_pagination_headers, unless: -> { @statuses.empty? }
 
+  before_action :require_user!, if: :require_auth?
+
   private
 
+  def require_auth?
+    !Setting.timeline_preview
+  end
+
   def pagination_collection
     @statuses
   end