[v9] Service providers should all $provide

[KorvinSzanto]

Service providers already have the ability to declare what it is that they provide via the $provides interface. This makes it so the container can lazy load service providers and only register the ones that are needed as part of a request potentially speeding up $app->make calls and the site significantly.

So what does a service provider look like that provides?

class ServiceProvider extends Provider
{

    public $provides = [
        Foo::class,
        Bar::class,
        FooBar::class
    ];

    public function register()
    {
        $this->app->bind(Foo::class, function() {
            return new Foo();
        });
        $this->app->bind(Bar::class, function() {
            return new Bar();
        });
        $this->app->bind(FooBar::class, function() {
            return new FooBar();
        });
    }

}

That's all. Now we can cache a lookup table and only register providers that need to be registered.

Considerations

• Many providers are registered without the use of a "registerer" class
  IE: (new CustomServiceProvider($app))->register()
  These will just work as they do today. Instead we should have a simple way to push providers onto the container, maybe something like $app->provide($provider)
• This may add cache level considerations
• Performance is the key benefactor, this must be profiled thoroughly.