main navigation menu entries should have a hover style

[atarix83]

Regarding the work on usability/accessibility done in #728 it's recommend the introduction of a color that contrasts with the background (the same green of the DSpace logo would be perfect), on the 'hover' of the elements of the 'main navigation bar' (not to be used anywhere else) to uniquely distinguish that elements, in order to associate that color to the most important navigation elements.

[tdonohue]

@atarix83 : I'm placing this in "Unscheduled" for now, as I'd want to hear back from our Accessibility analysis & tester feedback before scheduling this. I'm not sure myself if this is really required, but feedback is welcome.

[tdonohue]

Closing as this appears to be outdated. Main navigation entries now do have a hover style & changes to that style were not requested in the Deque Analysis in May 2021