[PyTorch] Avoid refcount bump in UnionType::canHoldType (#66693)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/66693
Passing a `TypePtr` by value causes an unnececssary refcount
bump. We don't need to take ownership, so `const Type&` is all we
need.
I considered providing a compatibility shim that takes `const
TypePtr&`, but doing so is dangerous because a
copy is required to convert from a more specific pointer like
`NoneTypePtr`.
ghstack-source-id: 140737081
Test Plan: CI
Reviewed By: suo
Differential Revision: D31691869
fbshipit-source-id: f766ce3234a28771c2a9ca4c284eb3f96993a3d0
