feat: add toBeCasedCorrectly arch test assertion

[SimonBroekaert]

What:

• Bug Fix
• New Feature

Description:

This PR adds a new arch test assertion that compares the file path and namespace casing with each other to detect casing errors.

As most developers work on Mac OS or Windows, which by default have case insensitive file systems, these casing spelling errors might not be caught until deployed on linux environments.

This feature helps solve this issue by comparing both namespace and file path with each other.

Important:

This PR depends on the following PR in the pest-plugin-arch plugin: pestphp/pest-plugin-arch#27

Example:

File path: app/Providers/AppServiceProvider.php

<?php

namespace App\providers

class AppServiceProvider {}

The wrongly cased namespace part 'providers' will not cause a 'Class not found' exception on Mac OS, but will on linux.

With this feature, we can add the following test:

arch()
    ->expect('App')
    ->toBeCasedCorrectly();

This will catch the miss-cased namespaces / file paths