My overview block: Add sort by short name

Case 1:   Check "Sort by Short Name"hidden when Moodle website prevented. Login as admin. Access to "Administration / Appearance / Courses" and make sure that "Display extended course names (courselistshortnames)" is off. Go to the Dashboard. Check that "Sort by Short Name" is not displayed in the sort list (only "Course name" and "Last accessed" should be displayed).   Case 2:   Check "Sort by Short Name" only visible when Moodle website allowed. Access to "Administration / Appearance / Courses" and enable "Display extended course names (courselistshortnames)". Go to the Dashboard. Check that "Sort by Short Name" is displayed in the sort list.   Case 3:  Check "Sort by Short Name" feature is working. Create the following Courses with Short name (<Fullname>/<Shortname>): Course1/C1 Course2/A Course3/C3 Choose "Sort by Short Name" from the dropdown. Check  that the course is sorted by short name (Course2 - Course 1 - Course 3).   Case 4:  Check the website reset back to "Sort by Full Name" when Moodle website's config changed. Access to "Administration / Appearance / Courses" and disable "Display extended course names (courselistshortnames)". Back to the dashboard and refresh the current page. Check the "Sort by Short Name" is hidden. Check the "Sort by Full name" is checked and the course list sorted correctly (Course1 - Course2 - Course3)