[quant][graphmode][fx][fix] Fix support for custom module (#59041)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/59041
Static quantization for Custom module support was removed in a previous refactor
https://github.com/pytorch/pytorch/pull/57519 since it's not covered by the test case
This PR re-enabled the test case and fixed the support
Test Plan: Imported from OSS
Reviewed By: vkuzo
Differential Revision: D28724866
fbshipit-source-id: 1974675b88b56a2173daf86965d6f3fb7ebd783b
