Add engine aware trait + interface

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Currently, when a service need the template engine, I have a code like this :

```php
class MyAwesomeListener implements EventSubscriberInterface
{
    /**
     * @var EngineInterface
     */
    protected $renderer;
    
    /**
     * @param ContactEvent $event
     */
    public function onMyAwesomeEvent(MyEvent $event)
    {
        // here I need to render a template
    }

    /**
     * @param $renderer
     */
    public function setRenderer(EngineInterface $renderer)
    {
        $this->renderer = $renderer;   
    }
}
```

With a trait, I just would like to reduce code to write and keep my classes skinny when a service need the template engine.