title: How to get project or root dir in Symfony 5
body: <p>I use Symfony 5 and Solarium. I want to get the project dir (or root dir) in my Controller (extends from AbstractController).</p>
  
  <p>I saw some anwers with kernel, creating new services, etc..</p>
  
  <p>But, isn't it just a function that call the project dir without creating some custom services etc..?</p>
  
  <p>Thanks ! </p>