User sees the average number of attempts taken for each graded and ungraded problem

[crathbun428]

User Story
As a course author, I want to see the average number of attempts taken to answer each problem in my course, so I have another way to determine problem difficulty.

Acceptance Criteria
Scenario: A course author sees the average number of attempts taken to answer each problem in the course on their course dashboard
Given I am a course author with X permissions
When I view the performance section of the course dashboard
Then I see the average number of attempts taken to answer each graded and ungraded problem in the course

[SoryRawyer]

I think this can be charted using the fact_problem_responses dataset in Superset.