[PyTorch] Add VariableVersion&& overload for TensorImpl::shallow_copy_and_detach (#48681)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/48681
This should reduce reference counting traffic when creating views.
The code duplication here is unfortunate and I'm open to suggestions on how to reduce it. It's especially regrettable that we create a footgun for subclasses of TensorImpl: they can accidentally override only one of the two overloads and get confusing behavior.
ghstack-source-id: 117896685
Test Plan: internal benchmarks
Reviewed By: ezyang
Differential Revision: D25259741
fbshipit-source-id: 55f99b16b50f9791fdab85cbc81d7cd14e31c4cf
