Remove Tensor.h, TensorMethods.h from src/core. (#27086)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/27086
This is a major source of merge conflicts, and AFAICT isn't necessary anymore (it may have been necessary for some mobile build stuff in the past).
This is a commandeer of #25031
Test Plan: Imported from OSS
Reviewed By: ljk53
Differential Revision: D17687345
Pulled By: ezyang
fbshipit-source-id: bf6131af835ed1f9e3c10699c81d4454a240445f