activitypub: use Activity.normalize() in several places instead of using Activity.get_by_ap_id() directly.

lib/pleroma/web/activity_pub/activity_pub.ex

@@ -30,7 +30,7 @@ defp check_actor_is_active(actor) do
   end
 
   def insert(map, local \\ true) when is_map(map) do
-    with nil <- Activity.get_by_ap_id(map["id"]),
+    with nil <- Activity.normalize(map),
          map <- lazy_put_activity_defaults(map),
          :ok <- check_actor_is_active(map["actor"]),
          {:ok, map} <- MRF.filter(map),

lib/pleroma/web/activity_pub/transmogrifier.ex

@@ -460,14 +460,7 @@ def prepare_outgoing(%{"type" => "Create", "object" => %{"type" => "Note"} = obj
   # Mastodon Accept/Reject requires a non-normalized object containing the actor URIs,
   # because of course it does.
   def prepare_outgoing(%{"type" => "Accept"} = data) do
-    follow_activity_id =
+    with follow_activity <- Activity.normalize(data["object"]) do
-      if is_binary(data["object"]) do
-        data["object"]
-      else
-        data["object"]["id"]
-      end
-
-    with follow_activity <- Activity.get_by_ap_id(follow_activity_id) do
       object = %{
         "actor" => follow_activity.actor,
         "object" => follow_activity.data["object"],
@@ -485,14 +478,7 @@ def prepare_outgoing(%{"type" => "Accept"} = data) do
   end
 
   def prepare_outgoing(%{"type" => "Reject"} = data) do
-    follow_activity_id =
+    with follow_activity <- Activity.normalize(data["object"]) do
-      if is_binary(data["object"]) do
-        data["object"]
-      else
-        data["object"]["id"]
-      end
-
-    with follow_activity <- Activity.get_by_ap_id(follow_activity_id) do
       object = %{
         "actor" => follow_activity.actor,
         "object" => follow_activity.data["object"],