New Rust API just dropped

[Ottatop]

Now with infinite% more async runtimes!

Hey glizzies and gobblers,

Local starch citizen here to let you know that the Rust API is actually not steaming 💩 anymore!

No more need for whatever CallbackVec was, and there's now an attribute macro so you don't have to prepend and append your config with setup code.

I've also added some quality-of-life functions so you don't have to type in stuff like win.props().whatever everywhere; this can be shortened to win.whatever().

This does means that all of the closures must be Send + 'static, but hey if you want to capture a reference go leak a Box or something

Also the docs are actually good now 👍

^{Now I can get to making the compositor somewhat usable haha}