Improve the functionality of untyped storage for privateuse1. (#100868)
Complete the implementation of the interface is_pinned() of untyped storage class for privateuse1.
And refactor the implementation in typed storage by untyped_storage.is_pinned().
Hi, @ezyang
This is another improvement of untyped storage for privateuse1, can you take a moment to review it? Thanks.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/100868
Approved by: https://github.com/kurtamohler, https://github.com/ezyang
