[package] _custom_import_pickler -> _package_pickler (#53048)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/53048
I am planning the custom pickler and unpicklers that we use as
semi-public interfaces for `torch.rpc` to consume. Some prefatory
movements here.
Test Plan: Imported from OSS
Reviewed By: Lilyjjo
Differential Revision: D26734594
Pulled By: suo
fbshipit-source-id: 105ae1161d90f24efc7070a8d80c6ac3d2111bea
