[quant][graphmode][fx] Support preserved_attributes in prepare_fx (#50306)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/50306
Test Plan: Imported from OSS
Reviewed By: supriyar
Differential Revision: D25857747
fbshipit-source-id: fac132fb36ed9cf207aea40429b5bc3f7c72c35d
