[reland][quant][eagermode] Move custom_module registration to prepare/convert_custom_config_dict (#46293) (#46364)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/46364
Test Plan:
Imported from OSS
Imported from OSS
Reviewed By: vkuzo
Differential Revision: D24322747
fbshipit-source-id: 4801ba1835fc805bf767fe9810b9edfa2ceeefb4
