feat: add subscriber platform plugin POC with learner dashboard course categorization API.

[pavanhalesh]

Overview

This PR introduces a platform plugin that exposes a new LMS API endpoint to retrieve and categorize a learner’s enrolled courses into:

• subscription_courses
• upgradeable_courses
• non_upgradeable_courses

This is a Proof of Concept to validate backend filtering and course categorization logic required for the Subscriber Learner Dashboard.

Implementation Details

• Created a new platform plugin under openedx/plugins/subscriber

• Registered plugin using entry_points and plugin_app configuration

• Implemented API endpoint:

  /api/subscriber/dashboard/courses/

• Fetches learner enrollments using CourseEnrollment model

• Applies subscription catalog and subscriber status logic

• Returns categorized course IDs as JSON response

Example Response

{
"subscription_courses": ["course-v1:edX+DemoX+Demo_Course"],
"upgradeable_courses": [],
"non_upgradeable_courses": []
}

@asharma4-sonata and @jsnwesson Please review my PR whenever you get a chance to look on this. Thank You.

[jsnwesson]

This is the part that we should clarify.

Assume that SUBSCRIPTION_COURSE_IDS will eventually be an API call that we make to the Subscription catalog that another team will create.

From that payload, we'll need to check for each course enrollment:

1. Is the course part of the Subscription catalog? If yes:
   a. Did the user fulfill either enrolling in the course after becoming a Subscriber or upgrading their audited course into their Subscription? (This is likely to mean that in the Enrollments payload we will know if the course is upgraded to a full-access.)
   • If yes to either, then this course falls under subscription_courses.
   • If no to either, then this course falls under upgradeable_courses
2. If no, then the course falls under non_upgradeable_courses.

There's an additional tricky part that I haven't confirmed with Kelly, which is what happens if prior to being a Subscriber the user fully upgraded a course. Where does that course live in these three categories? If the course technically is part of the Subscription catalog, does it go under subscription_courses? If it doesn't, does it go under non_upgradeable_courses even though it indeed is upgraded already? Maybe that 3rd category would be more accurately called non_subscription_courses. I don't know yet.