[5.5] Allow setting editor for Whoops

[m1guelpf]

Whoops allows defining an editor to open the file that caused the exception with it. This PR adds an option to set this.

Reference: Open Files In An Editor - Whoops.

[laurencei]

This has come up before.

You can just edit the app\Exceptions\Handler.php yourself:

public function whoopsHandler()
{
    $handler = parent::whoopsHandler();
    $handler->setEditor(config('app.debug_editor'));
    return $handler;
}

[antonkomarev]

Thanks for sharing this!