… of controllers and service factories (nicolas-grekas)

This PR was merged into the 5.1-dev branch.

Discussion
----------

[FrameworkBundle] Allow using the kernel as a registry of controllers and service factories

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| Deprecations? | no
| Tickets       | Fix #28992, fix #29997
| License       | MIT
| Doc PR        | -

This PR builds on #34873 and #34872 and allows using the `Kernel` as a registry of autowired controllers and service factories. The `ContainerConfigurator` passed to `configureContainer()` defaults to declaring autowired and autoconfigured services.

TL;DR: Silex is back but in a much more powerful way \o/

Here is a Kernel that just works and displays `Hello App\Foo` on the `/` route:
```php
class Kernel extends BaseKernel
{
    use MicroKernelTrait;

    protected function configureContainer(ContainerConfigurator $container): void
    {
        $container->services()
            ->load('App\\', '../src')
            ->set(Foo::class)
                ->factory([$this, 'createFoo']);
    }

    public function createFoo(Bar $bar)
    {
        return new Foo($bar);
    }

    protected function configureRoutes(RoutingConfigurator $routes): void
    {
        $routes->add('home', '/')->controller([$this, 'helloAction']);
    }

    public function helloAction(Foo $foo)
    {
        return new Response('Hello '.get_class($foo));
    }
}
```

Commits
-------

9c9b99c [FrameworkBundle] Allow using the kernel as a registry of controllers and service factories