[ReduceOp] ameliorate custom `__eq__` (#90088)
Improve the completeness of `ReduceOp.__eq__`.
Should support the equal operator with the first argument of `RedOpType` and the second of `ReduceOp` in a follow-up.
Fixes #90072
Pull Request resolved: https://github.com/pytorch/pytorch/pull/90088
Approved by: https://github.com/kwen2501
