Certificates: Create an API endpoint to generate certificates

[arslanashraf7]

As a Learner, I'd like to get my certificate generated in MITxOnline once I complete the course on edX

Summary

We need to create an API endpoint to generate certificates for users. Ideally, this endpoint should only need the user_id, course_id for generating the certificate. As an enhancement, we can make this API accept a list of users so that we can use this to generate the certificates in a bulk, although the current requirement would be satisfied with a single user.

This API endpoint should be behind an authentication layer. We need to decide upon the access (Either any authenticated or just the user with Admin access)

This API should be added to the certificates app that will be created as a result of #686

Dependencies:

This ticket depends upon #691

Designs and Mockups

None

Acceptance Criteria:

• An API endpoint that generates the certificate per user per course run

[arslanashraf7]

FYI, @rhysyngsun @pdpinch

[rhysyngsun]

See my comment on #690 (comment)

[pdpinch]

I don't think we need this if we go with #717. I'm going to label this "On Hold"