Make saved tensors default hooks thread local (#62909)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/62909
This PR makes saved tensors default hooks thread local.
This allows using default hooks in a multithreaded context.
Test Plan: Imported from OSS
Reviewed By: albanD
Differential Revision: D30165416
Pulled By: Varal7
fbshipit-source-id: 10a7d580661d3d94bdaf398c4e076b7bea11c16b
