Integration with Webpack Encore Bundle

[jordisala1991]

Feature Request

We need to try if we can integrate with Webpack Encore Bundle now that we are using Webpack Encore. This will probably go against 5.0 to avoid more BC breaks in 4.0.

We need to consider what happens with other Sonata Bundles that have scripts, and how we configure WebpackEncore Bundle to handle the build for our users (or let the user configure it) (or use a recipe to auto configure that?).

[jordisala1991]

I think adding another dependency is not a good idea, because it is not needed. Lets close for now.