refactor(ui): Migrate components to ui-next (#4930)

Co-authored-by: Dan Rukas <dan.rukas@gmail.com>

extensions/default/src/utils/addIcon.ts

@@ -1,8 +1,6 @@
-import { addIcon as addIconUI } from '@ohif/ui';
 import { Icons } from '@ohif/ui-next';
 
 /** Adds the icon to both ui and ui-next */
 export function addIcon(name, icon) {
-  addIconUI(name, icon);
   Icons.addIcon(name, icon);
 }