* Allow the more menu to be rendered as a tablist when needed.
* Let menu_navigation handle keyboard navigation only when
menu items are not rendered as dropdowns. Otherwise, leave
the keyboard navigation handling via the default handlers
(e.g. dropdown.js/aria.js/tab.js).
* When the more menu is rendered as a tablist, use aria-selected
for the selected tab. When it's rendered as a menu, use aria-current
for the selected menu item. (The menuitem role supports aria-current and
not aria-selected)
* Make sure that the active tab is tabbable by default.
* Submenu items should always have tabindex=-1
* Update behat to use css_element instead of xpath. Also, improved it
to consider that it is the active element that should be tabbable.
Co-authored-by: Shamim Rezaie <shamim@moodle.com>
