title: how to avoid symfony 4 for creating default folders in src
body: <p>How I can avoid creating folders like <code>Controller</code>, <code>Entity</code> and so on inside of <code>src</code> directory when I'm running <code>composer install</code> as I'm using different folder structure in my application and it's annoying to delete that folders each time I run <code>composer install</code> by the first time on some machine</p>