Unify OS-specific types' trait implementations #20260

There are quite few os-specific types definitions whose traits implementations are not consistent. With the work happening in OIBIT, I've tried to keep the implementations of built-in traits consistent for both unix and windows. Unfortunately, the test suite for these implementations is not unified, therefore there's a high chance that some types for window's implementation may have some traits implemented, whereas the unix's implementation doesn't.

In theory, we can assume that common types for these implementations should implement the same built-in types, therefore there should be tests that enforce this guarantee in a common place.

Some examples may be found in std::sys::{unix,windows}::{pipe,mutex}

This bug is to track the work there which impacts the stability of our standard library.