Shaku can be used without dyn traits

[AzureMarker]

Hello there! I'm the shaku dev, and noticed this new DI library. It looks pretty interesting. I especially like the various levels of scope available.

I noticed that under "Can be used without dyn traits" you list shaku as "No". In fact, shaku can be used without using trait objects as dependencies. It does require a manual implementation of Component (or Provider), but see the following example:

use shaku::{module, Component, HasComponent, Interface, Module, ModuleBuildContext};
use std::sync::Arc;

trait Service: Interface {}

// Just a normal struct, no associated trait
struct Dependency;

// A manual impl of Component is necessary because the derive automatically assumes
// the interface is a trait. This restriction could be relaxed in a future release, such that
// #[derive(Component)] + #[shaku(interface = Self)] works.
impl<M: Module> Component<M> for Dependency {
    type Interface = Self;
    type Parameters = ();

    fn build(_: &mut ModuleBuildContext<M>, _: Self::Parameters) -> Box<Self::Interface> {
        Box::new(Self)
    }
}

#[derive(Component)]
#[shaku(interface = Service)]
struct ServiceImpl {
    // Notice that there is no `dyn` here!
    #[shaku(inject)]
    dependency: Arc<Dependency>,
}

impl Service for ServiceImpl {}

module! {
    TestModule {
        components = [Dependency, ServiceImpl],
        providers = []
    }
}

fn main() {
    let module = TestModule::builder().build();

    let service: &dyn Service = module.resolve_ref();
}