Rename make_unannounce_data helper to make_undo_data

This makes it a bit more easier to adapt for unlikes as well in the
future.

lib/pleroma/web/activity_pub/activity_pub.ex

@@ -142,7 +142,7 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
 
   def unannounce(%User{} = actor, %Object{} = object, local \\ true) do
     with %Activity{} = activity <- get_existing_announce(actor.ap_id, object),
-         unannounce_data <- make_unannounce_data(actor, activity),
+         unannounce_data <- make_undo_data(actor, activity),
          {:ok, unannounce_activity} <- insert(unannounce_data, local),
          :ok <- maybe_federate(activity),
          {:ok, _activity} <- Repo.delete(activity),

lib/pleroma/web/activity_pub/utils.ex

@@ -279,9 +279,9 @@ defmodule Pleroma.Web.ActivityPub.Utils do
   end
 
   @doc """
-  Make unannounce activity data for the given actor and object
+  Make undo activity data for the given actor and object
   """
-  def make_unannounce_data(
+  def make_undo_data(
         %User{ap_id: ap_id} = user,
         %Activity{data: %{"id" => id, "context" => context}} = activity
       ) do