[PyTorch][codemod] Replace immediately-dereferenced cast calls w/castRaw (#50229)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/50229
`fastmod -m 'cast(<((at|c10)::)?\w+Type>\(\)\s*)->' 'castRaw${1}->'` Presuming it builds, this is a safe change: the
result of `cast()` wasn't being saved anywhere, so we didn't need
it, so we can use a raw pointer instead of a new `shared_ptr`.
ghstack-source-id: 120769170
Test Plan: CI
Reviewed By: SplitInfinity
Differential Revision: D25837494
fbshipit-source-id: 46319100dc0dfc78f6d2b45148207f83481f2ada
