User can view enrollment rate information for course plotted over time

[crathbun428]

User Story
As a course author, I want to view the enrollment rate information for my course plotted over time, so that I am able to view steep climbs in enrollment as one way of identifying when and how learners are finding out about and signing up for my course.

Acceptance Criteria
Scenario: A course author views the enrollment rate chart from the course dashboard
Given I am a course author with X permissions
When I view the enrollment rate chart on the course dashboard
Then I see the number of learners enrolling in my course plotted over time
And I am able to clearly identify date and date ranges easily from the chart

[SoryRawyer]

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