Make images deletable in edit-structure Ui

[sujitv19196]

Problem

Current Edit-structure Ui does not allow user to delete images or text We want to merge the functionality of the edit-structure and edit-chapter UIs

Solution/Deliverables

1. replace the current static images with the image previews used in the edit-chapter Ui
2. Add delete button that will remove the image from the I-Note to the right of the image
3. Have the deletions be reflected in the Ui

Mockup: https://www.figma.com/proto/OVKDEecxHeRruHC42ADXAQ/Edit-Structure?node-id=1-2&scaling=min-zoom&page-id=0%3A1

[sujitv19196]

implemented