show current academic courses and order them

Implemented filters for the following:
Case 1: the user has entered something under "Find course by Code".
List the courses whose course code matches the entered course code, in reverse chronological order.

Case 2: the user has not entered something under "Find course by Code".
If there is a value for "List courses by faculty", list all courses that belong to the entered faulty, in reverse chronological order.

Otherwise, list the student's joined courses (already done), in reverse chronological order.

@@ -554,1 +554,4 @@
     $student_id= $_SESSION['user_student_id'];
+    // current academic year - i.e 2021 - 2022 , so we will show in search result:
+    // course containing either 2021 or 2022 as academic year.
+    $oldest_academic_year = date('Y') - 1;