[FrameworkBundle] Allow using a ContainerConfigurator in MicroKernelTrait::configureContainer()

[nicolas-grekas]

Q	A
Branch?	master
Bug fix?	no
New feature?	yes
Deprecations?	no
Tickets	-
License	MIT
Doc PR	-

This PR is a continuation of #32937 (it reverts some parts of it that are not needed anymore). It builds on #34872 for now.

This PR allows using the PHP-DSL natively in our Kernel::configureContainer() methods.
It allows the same in our Kernel::configureRoutes() methods.

Both signatures are handled gracefully with no deprecations to let existing code in peace:

• protected function configureContainer(ContainerBuilder $c, LoaderInterface $loader);
• protected function configureContainer(ContainerConfigurator $c); (a loader is always passed as 2nd arg to ease FC)

Same for routes:

• protected function configureRoutes(RoutingConfigurator $routes);
• protected function configureRoutes(RouteCollectionBuilder $routes); (this one is deprecated because RouteCollectionBuilder is deprecated)

Here is my working src/Kernel.php after this change:

class Kernel extends BaseKernel
{
    use MicroKernelTrait;

    protected function configureContainer(ContainerConfigurator $container): void
    {
        $container->import('../config/{packages}/*.yaml');
        $container->import('../config/{packages}/'.$this->environment.'/*.yaml');
        $container->import('../config/services.yaml');
        $container->import('../config/{services}_'.$this->environment.'.yaml');
    }

    protected function configureRoutes(RoutingConfigurator $routes): void
    {
        $routes->import('../config/{routes}/'.$this->environment.'/*.yaml');
        $routes->import('../config/{routes}/*.yaml');
        $routes->import('../config/routes.yaml');
    }
}

[vudaltsov]

This is a great alternative to my deprecations! Learned a lot, thanx!