Make conversion methods consistent across the API

[KodrAus]

This PR removes the explicit Ref types for different formats in favor of casting a &Uuid. This is safe to do because the format types are #[repr(transparent)] and Copy.

I've also made the naming conventions consistent for all methods that produce and return Uuids and enhanced the docs.

[KodrAus]

@kinggoesgaming This basically changes our format adapters to be a single type. We make a reference to these types from a UUID when we want to avoid copying. This is a safe transmute because they’ve got the same ABI, implement Copy, and don’t implement Drop.