Implement IntoBytes for Option types? #596
Description
Similar to #293, we should ensure that it's guaranteed that Option<P> satisfies IntoBytes (where P is a pointer type which is subject to NPO), and emit an IntoBytes impl.
This is blocked on rust-lang/rust#117591, which guarantees that observing the bytes of a None::<P> is sound. It is also blocked on guaranteeing that observing the bytes of a Some::<P> is sound, which is effectively ptr2int.