Reflection for virtual `CodeIgniter\Entity\Entity` properties

[paulbalandan]

By default, PHPStan does not know what is the relation of $casts to the properties of Entities. We need to teach it that the content of $casts influence the type of the properties.

Originally posted by @paulbalandan in #7 (comment)

[paulbalandan]

Fixed in https://github.com/CodeIgniter/phpstan-codeigniter/tree/v2.0.0