Add custom treespec fqn field

Summary:
X-link: pytorch/pytorch#112428

Custom classes that are serialized with pytree are serialized by default with `f”{class.__module__}.{class.__name__}”`. This is a dependency from our serialized program directly into the outer Python environment. If a user moves the class to a different directory, the serialized program will be unable to be loaded. So, we will require users to pass in an FQN if they want to serialize their custom treespec type.

cc voznesenskym penguinwu EikanWang jgong5 Guobing-Chen XiaobingSuper zhuhaozhe blzheng wenzhe-nrv jiayisunx chenyang78 aakhundov kadeng avikchaudhuri gmagogsfm zhxchen17 tugsbayasgalan suo

imported-using-ghimport

Reviewed By: suo

Differential Revision: D50886366

Pulled By: angelayi

fbshipit-source-id: 276af112307e3d89137ff10af999ebeb5935a5ad

userbenchmark/dynamo/dynamobench/common.py

@@ -566,7 +566,10 @@ def _register_dataclass_output_as_pytree(example_outputs) -> None:
     for output_type in output_dataclass_types:
         from torch._export.utils import register_dataclass_as_pytree_node
 
-        register_dataclass_as_pytree_node(output_type)
+        register_dataclass_as_pytree_node(
+            output_type,
+            serialized_type_name=f"{output_type.__module__}.{output_type.__name__}",
+        )
 
 
 class Stats: