Add coursewide percentage correct to the Problem Results table on the Individual Learner Dashboard

[crathbun428]

User Story
As a course delivery team member, I want to see a new Course-wide % correct column in the Problem Results table on the Individual Learner Dashboard, so that I can easily compare how every learner in the course who answered a given problem performed versus one individual learner.

Acceptance Criteria
Given I have access to the Individual Learner Dashboard
When I view the Problem Results table
Then I see a new Course-wide % Correct column to the left of the % Correct column
And the % Correct column is renamed to Selected Learner % Correct
And (if possible) Visually indicate when Selected Learner % Correct is lower, equal to, or higher than Coursewide % Correct