Code-splitting setup should be updated to be compatible with latest webpack optimizations of code chunks

[birdofpreyru]

[birdofpreyru]

It turns out that chunk splitting optimization makes quite cumbersome the correct injection of CSS assets during the server-side rendering. Thus, the change above is reverted, and the fix will be postponed (probably, in future versions of Wepback they will add functionality that will make it easy, so we better wait).