UI: Look at the clicking on submenus at CascadingMenu for Teacher

[MathiasHandeland]

• When clicking "move to cohort" this parent component should persist on the page and still be displayed when the child submenu for example "software development" is clicked
• Do this: Clicking outside any menu automatically closes it (handled in CascadingMenuProvider except if you click on a menu that has submenus ("arrowright")