This is part of the effort to support the new embedded Studio Unit Page. It includes changes to the CourseUnit component and the functionality of interaction between xblocks in the iframe and the react page.
The following events have been processed:
* delete event
* Manage Access event (opening and closing a modal window)
* edit event for new xblock React editors
* clipboard events
* duplicate event
* feat: Course unit - add new component section
* feat: Course unit - make Discussion and Drag-and-Drop button functional
* feat: Course unit - make Problem button functional
* feat: Unit page - make Video button functional
Also refactor api and hooks
fix: publish button behaviour and card header tests
fix: warning in highlights and publish modal test
fix: courseoutline tests
test: add test for new section functionality
fix(lint): lint issues
refactor: remove unnecessary css in CardHeader
refactor: rename emptyPlaceholder test file
refactor: replace ternary operator with 'and' condition
refactor: add black color to expand/collapse button
refactor: display only changed subsection and units in publish modal
refactor: update messages and css
refactor: wrap urls in function call
refactor: fix jsdoc types
refactor: use helmet for document title
