Add hash and int128 utils for Lazy Tensor Core (#65635)
Summary:
These utils are prerequisites for Lazy Node base class.
- set up new torch/csrc/lazy, test/cpp/lazy dirs
- add source files to build_variables.bzl in new lazy_core_sources var
- create new test_lazy binary
Fixes https://github.com/pytorch/pytorch/issues/65636
Pull Request resolved: https://github.com/pytorch/pytorch/pull/65635
Reviewed By: alanwaketan
Differential Revision: D31260343
Pulled By: wconstab
fbshipit-source-id: 8bb1194188e3e77fc42e08a14ba37faed37a9c2e
