Discover New tab should be hidden when COURSES_ARE_BROWSABLE is set to False

[Danyal-Faheem]

The Learner Dashboard MFE shows the Courses and Discover New tab in the header when programs and support link is not configured.

However, when FEATURES['COURSES_ARE_BROWSABLE'] is set to false, the Discover New tab is still shown. I understand that this feature was meant to modify the old LMS mako templates but I believe that Open edX users would still like a similar feature for the Learner Dashboard MFE especially since it is the default homepage for learners.

Is it possible to add a MFE_CONFIG setting in the learner dashboard mfe to hide the Discover New tab similar to the work done for programs and support link in #506 and #469?