feat: custom build hooks

[StrikeForceZero]

Summary

This gives users the ability to hook the auto plugin build function by implementing AutoPluginBuildHook for their own hooks

Examples:

Unit

#[derive(AutoPlugin)]
#[auto_plugin(impl_plugin_trait)]
struct TestPlugin;

struct MyCustomHookUnit;

impl<T: Component + 'static> AutoPluginBuildHook<T> for MyCustomHookUnit {
    fn on_build(&self, app: &mut App) {
        // access to T for any type-related plumbing e.g. registering types
       app.register_type::<T>();
    }
}


#[derive(Component, Debug)]
#[auto_plugin_build_hook(plugin = TestPlugin, hook = MyCustomHookUnit)]
struct TestComponent;

Instance

#[derive(AutoPlugin)]
#[auto_plugin(impl_plugin_trait)]
struct TestPlugin;

struct MyCustomHookInstance(&'static str);

impl<T: Component + 'static> AutoPluginBuildHook<T> for MyCustomHookInstance {
    fn on_build(&self, app: &mut App) {
        // access to T for any type-related plumbing e.g. registering types
       app.register_type::<T>();
       // or access the hooks instance
       println!("{}", self.0);
    }
}


#[derive(Component, Debug)]
#[auto_plugin_build_hook(plugin = TestPlugin, hook = MyCustomHookInstance("bar"))]
struct TestComponent;

TODO:

• add documentation