Frontend: Add feedback trigger to nav bar

Created by: quinnkeast

Part of implementing RFC 215: Improving User Feedback.

Description

Add the feedback item to the nav bar / menu.

Note that the menu as a whole has changed since initial design: placement of button remains the same as in design specification.

Interaction details can be found in the Figma docs. As a highlight: hovering over the button should trigger the text cursor, not the pointer.

When clicked, reveals the omnipresent feedback widget (#17645 (closed))

Note: Should not collapse into the dropdown menu on smaller screen sizes.

Design documentation:

• View in Figma