Foldable navigational menus

Could collapsable/foldable menus be implemented? Similarly to the internal handbook: https://gitlab.com/internal-handbook/internal-handbook.gitlab.io/-/merge_requests/1796

Maybe this styles could be implemented: https://design.gitlab.com/components/accordion/code

This request is to support this MR: Draft: Display operating principles in the righ... (!119166 - closed)

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