Application Panel "More Applications" dropdown is not accessible

The "Applications" panel is a navigation panel. It contains mainly links, which is alright, but at the end it contains one link that shows/hides some content when clicked. This element should not be a link but a button, because:

• A link allows the user to move, a button allows an action. Here, the user doesn't move, but opens up a drop-down.
• The class of this anchor already depicts it as a button.

Changing the nature of this element will make it more clear for screen reader users when going through the content of the panel, and users will understand that this element is a drop-down toggle easier if the style is distinct from regular links.

The appropriate aria attributes should be set on this dropdown/disclosure pattern.

Notes:

• The solution should use the <button> HTML instead of role="button" from ARIA.
• A pattern adapted to this element is available on the W3.org website: https://www.w3.org/WAI/ARIA/apg/patterns/disclosure/examples/disclosure-faq/