Fix T69176: Outliner->BlenderFile->Delete not working on some objects.

Object not referenced in any scene would not be deletable with previous
code... that was fine in 2.7x since it was not supposed to happen, but
now we can just use the nuclear `BKE_id_delete` for objects as well,
will take care of properly unlinking everything as needed.

source/blender/editors/space_outliner/outliner_tools.c

@@ -680,7 +680,7 @@ static void object_delete_cb(bContext *C,
     if (ob == CTX_data_edit_object(C)) {
       ED_object_editmode_exit(C, EM_FREEDATA);
     }
-    ED_object_base_free_and_unlink(CTX_data_main(C), scene, ob);
+    BKE_id_delete(bmain, ob);
     /* leave for ED_outliner_id_unref to handle */
 #if 0
     te->directdata = NULL;