[5.7] Allow the app path to be configured

[rojtjo]

In my recents projects I'm using a different structure and I noticed I was not able to change the app path without subclassing the Application class.

This change allows the app path to be configured just like the database, environment and storage paths.

The reason I did not add a test for this method is because I could not find any tests for the other methods. If needed I'm happy to add them.

[BassemN]

Thanks a lot for that feature 👍
Is there any documentation for how using this feature?

[rojtjo]

The actual method was renamed to useAppPath. (see d73e672)

The way I use it is by calling it in the bootstrap/app.php (https://github.com/laravel/laravel/blob/master/bootstrap/app.php) file directly after the Application instance is created.

$app = new Illuminate\Foundation\Application(
    $_ENV['APP_BASE_PATH'] ?? dirname(__DIR__)
);

$app->useAppPath(__DIR__ . '/../src/App');

[BassemN]

@rojtjo Many thanks