Add detection of overridden deprecated properties

[jnoordsij]

Feature request: When overriding a class property in a child class, that is marked as deprecated in the parent class, a warning should be given. Currently only accessing such properties within methods of the child class triggers this warning.

This would be particularly useful for cases where an upstream package marks a property as deprecated, and where the intended method of setting the property is through overriding it with a new (default) value within the child class, without explicitly accessing it in any method on the child class.

A real world example of such a case is the planned removal of the dates property in Laravel, which won't be detected as a deprecated property currently when overriding it. A code example that currently does not yield any warning:

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Foo extends Model
{
    protected $dates = ['foo'];
}