[PyTorch] Use intrusive_ptr to save space in KernelFunction (#65618)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/65618
This saves 8 bytes per KernelFunction, which should help in resource-constrained environments.
ghstack-source-id: 140731069
Test Plan: CI
Reviewed By: ezyang
Differential Revision: D25405736
fbshipit-source-id: 757c0f1387da9147e46ac69af2aa9fffd2998e35
