Change how closed course run are shown

[2018D]

Feature Request

Is your feature request related to a problem or unsupported use case? Please describe.
All closed course run presently show start and end date.
After feedback from users, future closed run would be better served if showing enrollment date.
Users should know when course run is available for enrollment and when more details will be available.

Describe the solution you'd like
Show enrollment date for all closed course runs instead of course start and end date.

Describe alternatives you've considered
Show enrollment date only for future closed course run.

Discovery, Documentation, Adoption, Migration Strategy

Do you want to work on it through a Pull Request?
I have a branch for showing enroll date for all closed run https://github.com/EDUlib/richie/tree/enrollDateCourseRun
Extra logic would be required for showing enroll date on only future closed course run. I am working on it but will stop if this solution is preferred.