feat: optionally emit course completion analytics when a learner enters the courseware (#36507)

This PR attempts to improve the ability to collect analytics about learner's progress
in their courses. Currently, the only place we regularly calculate course progress is
when a learner visits the "Progress" tab in the courseware.

Now, _optionally_, when a learner visits the home page of their course, we will enqueue
a Celery task that will calculate their progress and emit a tracking event.

This event is gated by use of the COURSE_HOME_SEND_COURSE_PROGRESS_ANALYTICS_FOR_STUDENT
waffle flag.

lms/djangoapps/course_home_api/progress/api.py

@@ -0,0 +1,43 @@
+"""
+Python APIs exposed for the progress tracking functionality of the course home API.
+"""
+
+from django.contrib.auth import get_user_model
+from opaque_keys.edx.keys import CourseKey
+
+from lms.djangoapps.courseware.courses import get_course_blocks_completion_summary
+
+
+User = get_user_model()
+
+
+def calculate_progress_for_learner_in_course(course_key: CourseKey, user: User) -> dict:
+    """
+    Calculate a given learner's progress in the specified course run.
+    """
+    summary = get_course_blocks_completion_summary(course_key, user)
+    if not summary:
+        return {}
+
+    complete_count = summary.get("complete_count", 0)
+    locked_count = summary.get("locked_count", 0)
+    incomplete_count = summary.get("incomplete_count", 0)
+
+    # This completion calculation mirrors the logic used in the CompletionDonutChart component on the Learning MFE's
+    # Progress tab. It's duplicated here to enable backend reporting on learner progress. Ideally, this logic should be
+    # refactored in the future so that the calculation is handled solely on the backend, eliminating the need for it to
+    # be done in the frontend.
+    num_total_units = complete_count + incomplete_count + locked_count
+    complete_percentage = round(complete_count / num_total_units, 2)
+    locked_percentage = round(locked_count / num_total_units, 2)
+    incomplete_percentage = 1.00 - complete_percentage - locked_percentage
+
+    return {
+        "complete_count": complete_count,
+        "locked_count": locked_count,
+        "incomplete_count": incomplete_count,
+        "total_count": num_total_units,
+        "complete_percentage": complete_percentage,
+        "locked_percentage": locked_percentage,
+        "incomplete_percentage": incomplete_percentage
+    }