Add guards for using named tensor with serialization and multiprocessing (#25345)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/25345
Test Plan
- New tests [namedtensor ci]
Test Plan: Imported from OSS
Differential Revision: D17101486
Pulled By: zou3519
fbshipit-source-id: 58e803b042056ee6abab8551517f74078f2b81d5
