Closes#17245 and #17253
When the user selects a doc item in the side nav:
1) expand folder(s) leading to the selected doc item
2) on a wide display, keep other already expanded folders open
3) on narrow (mobile) display, collapse other expanded folders
Used to do (3) when wide. Issue #17245 asks for (2).
That logic was bypassed for selected node when we allowed headers to have content
because that unintentionally expanded the header’s folder when selected.
Because the selected node is no longer a header with content, removing this exclusion
also means that folders are expanded/collapsed with above logic even for API pages.
2d5623911a