[DESCRIPTION: 

Add shadow into top bar in page builder. We currently do not have a shadow (we have eliminated it). However, in development, the top bar is not clearly separated from the content - a gray line alone is not enough.

Let's add a shadow the same as in the tooltip. 

Additionally, we have two icons to replace: for page blocks and structure view. Icons can also be found in the library

https://www.figma.com/file/WLjvvLskcZaNAxrOcSHBUt/UX-improvements-in-4.6-LTS-%2F-Drag-and-drop-experience-in-Page-Builder?type=design&node-id=5450%3A112010&mode=design&t=ViOcU853YB4vdhuk-1