[ResourceBundle] allow easier custom resources

[dpfaffenbauer]

Q	A
Bug fix?	no
New feature?	yes/
BC breaks?	no
Deprecations?	no

Allows you to define custom resources without the need of a DI Extension like:

Pimcore Models

core_shop_resource:
    pimcore:
        app.test:
            path:
                test: test
            classes:
                model: Pimcore\Model\DataObject\Test
                interface: App\Model\TestInterface

Doctrine Entities

core_shop_resource:
    resource:
        app.doctrine_test:
            classes:
                model: App\Entity\DoctrineTest
                interface: App\Model\DoctrineTestInterface
                repository: CoreShop\Bundle\ResourceBundle\Doctrine\ORM\EntityRepository

You than have access to services like factory or repository like:

$container->get('app.repository.test');
$container->get('app.repository.doctrine_test');

$container->get('app.factory.test');
$container->get('app.factory.doctrine_test');