(de)serialization of values between C++ and Python (#30108)
Summary:
This PR updates `torch::pickle_save` to use the new zipfile format introduced in #29232 and adds `torch::pickle_load` which can decode the zipfile format. Now that `torch.save/load` use this format as well (if the `_use_new_zipfile_serialization` flag is `True`), raw values saved in Python can be loaded in C++ and vice versa.
Fixes #20356
](https://our.intern.facebook.com/intern/diff/18607087/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/30108
Pulled By: driazati
Differential Revision: D18607087
fbshipit-source-id: 067cdd5b1cf9c30ddc7e2e5021a8cceee62d8a14
