move extension helper functions to separate files

packages/core/src/utils/getTopNodeFromExtensions.ts

@@ -0,0 +1,10 @@
+import collect from 'collect.js'
+import { Extensions } from '../types'
+
+export default function getTopNodeFromExtensions(extensions: Extensions): any {
+  const topNode = collect(extensions).firstWhere('topNode', true)
+
+  if (topNode) {
+    return topNode.name
+  }
+}