Rewrite the main function

[TheRustifyer]

Created the #[canyon] macro, that rewrites the code inside the main function.

Avoids the user to specify the async modifier, and to invoke the proc-macro #[tokio::main], now it's wired by `#[canyon] automatically.

It's been setted up the macro's crate to allow the creation of a new macro that will registers the structures managed by Canyon on a global namespace, allowing Canyon to know what data it has to care about in it's complete lifecycle