Refactoring Rust API traits and trying restart macOS/Metal development

Описание: Development on my graphics engine hotline in Rust. I'm rebooting my macOS and Metal backend but first I needed to tidy up some changes spread across different branches and get both the windows and macOS builds back in sync.

A little bit of a frustrating one here, as messy branch merges complicate things and changes to mutability and traits mean you have a lot of knock-on changes to make inside a trait implementation not just the interface.

Progress non the less and hopefully