Tensor reinitialization codemod - 2/5 (#15947)

Tensor reinitialization codemod - 2/5 (#15947)

Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15947

Codemod generated with clangr shard mode, 25 files per diff,
To eliminiate partially initialized Tensor, we split the initialization of local Tensor variables into two steps, first declare un uninitialized Tensor, and
call `ReinitializeTensor` to initialize it.
motivation: https://github.com/pytorch/pytorch/pull/12407

Reviewed By: smessmer

Differential Revision: D13586732

fbshipit-source-id: 5295ab27ca0155f96a4fccf9c0ba8a609101ba24