Add Lazy Tensor codegen infra (#69020)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/69020
Merges the lazy tensor codegen infra which has already been used on lazy_tensor_staging.
Test Plan: Test via lazy_tensor_staging branch
Reviewed By: alanwaketan, bdhirsh
Differential Revision: D32570613
fbshipit-source-id: 2cd5698644398bda69669683f8de79fd3b6639b5
