Add 'Move to' option to the section kebab menu in the course index

As a teacher
I want to be able to move an existing section to another position
so I can order course content

This option will move the current section to a different place in the same course.

(forget about the rest of options for now)

Prototype: There is no specific prototype to move sections, so pointing to https://www.figma.com/proto/OfCvqK069Oz6Fvqq2xcZWI/Create-a-course?node-id=2905%3A744&scaling=min-zoom

Acceptance criteria:

1. A modal should be shown for the user to choose the destination.

1. 1. User will see the whole structure of the course in the modal (similar to the course index)
   2. Selecting an activity or section will enable the ‘Move’ button.
   3. The section’s new destination will be a position after the selected section, or after the section where the activity is part of.
   4. All sections except the selected one (the source) will be collapsed.
   5. All labels will be shown in the modal. ‘(Untitled)’ will be shown for labels with empty title.
   6. Per UX decision this option won't allow user to move a section to the first position.
2. Once the action is finished:
   1. The user stays in the same ‘source’ position.
   2. A toast notification will be shown once the action has been completed.

Technical tasks:

• "Move to" and "Copy to" modal component
• Add section_move state actions