Delisting unavailable pinned courses

[KemalKrKX]

Motivation and Context

(#1351)

Description

The code preloads the students when preloading the course, so that if a student is not enrolled at said course/doesn't have the view right the pinned lecture is not displayed anymore.

Steps for Testing

Prerequisites:

• 1 Lecturer
• 1 Students
• 1 Lecture

1. Create a course
2. Enroll a student to said course
3. Pin the course as the student
4. Set the course as enrolled only and remove the student from database
5. Student should not see the course pinned anymore

[github-actions]

Your Testserver will be ready at https://1420.test.live.mm.rbg.tum.de in a few minutes.

Logins

Kurs1	Kurs2	Kurs3	Kurs4
public	public	loggedin	enrolled
prof1	prof1	prof2	prof1 prof2
student1 student2 student3	student1 student2	student2 student3	student1 student2