Navbar My courses and Site admin Courses have the same data-key

The data-key for the new main navbar item "My Courses" and the Site administration menu item "Courses" both have the data-key="courses".

Thus hiding the main My courses via CSS (just as we used to do with the Boost Navdrawer) will also hide the Site admin entry.

Suggest to name the key for "My Courses" to "mycourses".

To reproduce:

Log in as administrator.
View Navbar My courses in the browser inspector.
View Site admin menu item Courses in browser inspector.