Fetch attributes from parent classes to allow reusability

[bastien-phi]

This PR changes class attributes resolution fetching parent classes attributes as well as current class attributes.

This allows the developer to factorize attributes declarations parent classes.

For example if we want every data to be mapped with SnakeCaseMapper, we currently need to declare #[MapName(SnakeCaseMapper::class)] on every single Data class.

With this PR, we can declare a BaseData with the mapper and every child class with inherit with the mapper.

#[MapName(SnakeCaseMapper::class)]
abstract class BaseData extends Data {}

class MyData extends BaseData {
    public function __construct(
        public string $firstName,
    ) {}
}

MyData::from(['first_name' => 'John']); // work as expected

In case the attribute is redeclared in child class, the child attribute has higher priority (parents attributes are push at the end of the collection).

[rubenvanassche]

Looking good, some small changes required

[rubenvanassche]

You want to check on the BaseData interface here, since in v4 we'll have mutliple base Data classes like Dto and Resource.

[bastien-phi]

I decided not to exclude base class provided by the package here. Easier way, not sure if we can exclude base class based on an interface it implements as the child class will also implements this interface...

[bastien-phi]

@rubenvanassche This should be better

[rubenvanassche]

Looking great! Thanks!

[bastien-phi]

Thank you !