Hide coaches/staff/instructors from coach's enrollment tab, gradebook, grades csv file

[amir-qayyum-khan]

Background

Fixes #243

What is done in this PR

Studio Updates: None.
LMS Updates:

• Now showing ccx members in coach enrollment tab exculding staff, instructor and coach on master course.
• Hid staff, instructors and coach from gradebook
• Hid staff, instructors and coach from gradebook csv file

@pdpinch @giocalitri

To test:

• Create a course
• Add staff, instructors and coaches to the course.
• Create CCX
• See enrollment page in coach dashboard their should be no staff and instructors
• Open gradebook and see list of student make sure their are no staff, instructors and coaches
• Download gradebook csv and check their should no staff, instructors and coaches of master course

[pdpinch]

I wonder if someone else has already added this functionality upstream to edX?

[amir-qayyum-khan]

I dont think so. This issue still exist on edX master

cc @tasawernawaz

[pdpinch]

Ok, I'll take this over and either close or reassign it.