[Feature] [Low Priority] Only write review for Professor if Professor has ever taught the course

[Jjmaxxx]

Figure out how to make it so users can only write reviews for specific courses if that professor has ever taught that course before. Needs to keep track of past and present semesters. One way might be to update an attribute that holds a list for each professor that we update every time a new schedule is inserted to the db, but we can discuss if there's a better way to implement this.