IBX-9627: Implemented Ibexa Rector config factory

[alongosz]

🎫 Issue	IBX-9627

Related PRs:

• IBX-9627: [GHA] Created Rector PHP reusable workflow gh-workflows#56

Description:

To avoid repetition of rector.php contents in all packages, related to enabling Rector on CI, introducing IbexaConfigRectorFactory SPI.

Usage:

use Ibexa\Contracts\Rector\Factory\IbexaRectorConfigFactory;

return (new IbexaRectorConfigFactory(
    [
        __DIR__ . '/src',
        __DIR__ . '/tests',
    ]
))->createConfig();

That way if Rector sets change, we can change it here instead of in all packages.

[alongosz]

Note: this one is about container->get usages in favor of direct service injection.

[konradoboza]

+1 but readonly should be probably moved to each class property.