Implement on-platform courses in Physionet

[Rutvikrj26]

This is a three part-series consisting of implementing the ability to conduct on-platform training and exams (a mini-LMS).

• Part 1: Implementing the ability of upload and manage course versions (create training basics --> Add create training from admin console by uploading json #1950) - Merged
• Part 2: Implementing the ability to take an available course for getting a certification (create training basics --> implement take training feature and resume training feature for user #1951) - Merged
• Part 3: Updating the certification page to show the on-platform trainings in-progress, active, and expired. (Updating the Certification Page for course based trainings #2223) - WIP

[Rutvikrj26]

Updating the certifications page requires two changes:

updating the queryset fetching all the trainings in different stages for the user to now also include on-platfrom courses. (Done)
Updating the UI to inlcude the on-platform courses.
The courses that are completed, and for which the training has been approved for the user - we can easily include under the active stage, but the courses under progress, still need to shown in some other place.

change for the UI - Add an in-progress tab that shows the on-platform training that are currently being taken.