Add ability to hide courses from the course overview page

Using a Site 3.6. Check in the dashboard the course download button is not there anymore and it shows a menu. Open the menu and hide or show any course. Check in the block course overview the course is correctly shown (in hidden if you hide it) in any other if you show it. Do a PTR and check that the block course overview shows the courses as expected (hidden ones only visible when the hidden filter selected, etc..) Close the app, enable the Airplone mode in your phone so the device is offline, access the course and check that the block display the courses as expected Check in 3.5 or previous version the download button on courses is still there.