[quant][fx][graphmode] Add prepare_custom_config_dict and convert_custom_config_dict (#46223)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/46223
Also move standalone module config to the prepare_custom_config_dict
Test Plan: Imported from OSS
Reviewed By: vkuzo
Differential Revision: D24266900
fbshipit-source-id: fe3ff5b8c657af3f377041e7881d400938e044f8
