Submissions: sort by courses and courses label

[samuelchen1213]

Added UI:
I believe it would be much easier for an admin to mark different tests or view surveys if they are able to view which test/survey is from which courses (Having another row to dedicate to course name). Also they should also be able to sort them by courses as it would be much clearer for them to mark tests. For example, if they plan to focus on one courses at a time, they would not have to be distracted by other course tests.

[lmmrssa]

@samuelchen1213 submissions are related to exams and that is what most of time it will be looked through. Also in future we would like to link same exam to multiple courses. So in that case showing course will not be relevant.