[People] Allow Differentiation Tags to Course Roles Other than Student

[jfountain]

Problem statement:

We'd like the ability to assign Differentiation Tags to course roles other than Student. This would be useful when assigning specific teachers to specific tagged students for course activities such as mentoring and tutoring.

Proposed solution:

Allow tagging for any course role and not just Student.

User role(s):

admin,instructor,ta