This pull request adds support for class_alias to Tinker's configuration.

Motivation:
We created a model App\Models\Event, which conflicts with the events facade. As a result, instead of the Event model class being aliased, the events facade was aliased.

This solution allows users to map the conflicting class name to another class. For example, in config/tinker.php.

<?php

return [
    'class_alias' => [
        'AppEvent' => App\Models\Event::class,
    ],
];