`NonZeroUX` should implement `ZeroableOption`

[Darksonn]

This would let us get rid of:

pin-init/src/lib.rs

Lines 1632 to 1637 in 871cf88

	// SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee:
	// <https://doc.rust-lang.org/stable/std/option/index.html#representation>).
	Option<NonZeroU8>, Option<NonZeroU16>, Option<NonZeroU32>, Option<NonZeroU64>,
	Option<NonZeroU128>, Option<NonZeroUsize>,
	Option<NonZeroI8>, Option<NonZeroI16>, Option<NonZeroI32>, Option<NonZeroI64>,
	Option<NonZeroI128>, Option<NonZeroIsize>,

[BennoLossin]

That's a good suggestion, I'll take a look and see if I can fit this in my December schedule... Feel free to make it a good-first-issue on the RfL repo & direct people here.