Multi-Instructor course is not handled properly by backend lists

[BenceBertalan]

We wanted to use the Multi-instructor TutorLMS addon to have the ownership of a course split between a team of instructors.
We did a few testing rounds, and it turned out that the backend for most tutor functions (courses, assignments, quizes) does not handle multi-instructor plugin assigned instructors: Only the creator owner of the course can see the course and all of it's assignments/quizes (and the submitted assignments and quizes aswell).
We would like to see that all the backend functionality checks if the multi-instructor addon is turned on, and modifies the list fuction to properly show the course and all it's related assignments/quizes to all the members of the instructor group assigned to a course.