Respect custom model implementations in Schemas

[theimerj]

Problem:

Right now we use Lunar models like so:

// ...

use Lunar\Models\Order;

class OrderSchema extends Schema
{
    /**
     * {@inheritDoc}
     */
    public static string $model = Order::class;
    
    // ...

That means that we do not have direct access to custom model features as well as correct LSP support.

Solution:

• Try to swap model implementation as described here probably on the Laravel Json API Eloquent repository level?