[package] PackageExporter `__import__` logic to not parse dynamic cases (#57283)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/57283
Test Plan: Imported from OSS
Reviewed By: suo
Differential Revision: D28095858
Pulled By: Lilyjjo
fbshipit-source-id: c3cec074e6b2c48a09785fa0c02cd576b7ec94d9
