activitypub: move post rich media fetching to job queue

lib/pleroma/web/activity_pub/activity_pub.ex

@@ -133,9 +133,7 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
           activity
         end
 
-      Task.start(fn ->
-        Pleroma.Web.RichMedia.Helpers.fetch_data_for_activity(activity)
-      end)
+      PleromaJobQueue.enqueue(:background, Pleroma.Web.RichMedia.Helpers, [:fetch, activity])
 
       Notification.create_notifications(activity)
 

lib/pleroma/web/rich_media/helpers.ex

@@ -34,4 +34,6 @@ defmodule Pleroma.Web.RichMedia.Helpers do
   end
 
   def fetch_data_for_activity(_), do: %{}
+
+  def perform(:fetch, %Activity{} = activity), do: fetch_data_for_activity(activity)
 end