Add sortorder as public field on core_course_get_courses_by_field

Prepare the environment: Create two courses and one user. Enrol the user to one of the courses as a student. Enable "Mobile services": Site administration ► Mobile app ► Mobile settings ► Enable web services for mobile devices (or search enablemobilewebservice setting). Create a Token for the student: Click on Site administration ► Plugins ► Web services ► Manage tokens. Test: Next, you can do a CURL REST call simulating a WS client with the student user. You need to replace the wstoken and the URL of your moodle instance: curl 'http://localhost/m/stable_master/webservice/rest/server.php?moodlewsrestformat=json' --data 'wsfunction=core_course_get_courses_by_field&wstoken=ffbe3a3002f235bf9d01fd9369e10b66' --compressed Confirm that the sortorder field is returned on both courses of the list returned.