feat: allow unsubcribing from a course goal with just a token

* Add unsubscribe_token uuid field to CourseGoal model
* Add endpoint to unsubcribe from just a token (no login needed)
* Add admin page for the course_goals djangoapp
* Add get_course_overview_or_404 utility method
* Clean up URL handling in course_home_api

AA-907

openedx/core/djangoapps/content/course_overviews/api.py

@@ -3,6 +3,8 @@ CourseOverview api
 """
 import logging
 
+from django.http.response import Http404
+
 from openedx.core.djangoapps.catalog.api import get_course_run_details
 from openedx.core.djangoapps.content.course_overviews.models import CourseOverview
 from openedx.core.djangoapps.content.course_overviews.serializers import (
@@ -25,6 +27,18 @@ def get_course_overview_or_none(course_id):
         return None
 
 
+def get_course_overview_or_404(course_id):
+    """
+    Retrieve and return course overview data for the provided course id.
+
+    If the course overview does not exist, raises Http404.
+    """
+    try:
+        return CourseOverview.get_from_id(course_id)
+    except CourseOverview.DoesNotExist as e:
+        raise Http404(f"Course overview does not exist for {course_id}") from e
+
+
 def get_pseudo_course_overview(course_id):
     """
     Returns a pseudo course overview object for a deleted course.

openedx/core/djangoapps/content/course_overviews/tests/test_api.py

@@ -3,11 +3,13 @@ course_overview api tests
 """
 from mock import patch
 
+from django.http.response import Http404
 from opaque_keys.edx.keys import CourseKey
 
 from openedx.core.djangoapps.catalog.tests.factories import CourseRunFactory
 from openedx.core.djangoapps.content.course_overviews.models import CourseOverview
 from openedx.core.djangoapps.content.course_overviews.api import (
+    get_course_overview_or_404,
     get_course_overview_or_none,
     get_course_overviews,
     get_course_overviews_from_ids,
@@ -27,7 +29,7 @@ class TestCourseOverviewsApi(ModuleStoreTestCase):
         for _ in range(3):
             CourseOverviewFactory.create()
 
-    def test_get_course_overview_or_none(self):
+    def test_get_course_overview_or_none_success(self):
         """
         Test for `test_get_course_overview_or_none` function when the overview exists.
         """
@@ -43,6 +45,22 @@ class TestCourseOverviewsApi(ModuleStoreTestCase):
         retrieved_course_overview = get_course_overview_or_none(course_run_key)
         assert retrieved_course_overview is None
 
+    def test_get_course_overview_or_404_success(self):
+        """
+        Test for `test_get_course_overview_or_404` function when the overview exists.
+        """
+        course_overview = CourseOverviewFactory.create()
+        retrieved_course_overview = get_course_overview_or_404(course_overview.id)
+        assert course_overview.id == retrieved_course_overview.id
+
+    def test_get_course_overview_or_404_missing(self):
+        """
+        Test for `test_get_course_overview_or_404` function when the overview does not exist.
+        """
+        course_run_key = CourseKey.from_string('course-v1:coping+with+deletions')
+        with self.assertRaises(Http404):
+            get_course_overview_or_404(course_run_key)
+
     def test_get_course_overview_from_ids(self):
         """
         Test for `get_course_overviews_from_ids` function.

openedx/core/djangoapps/courseware_api/serializers.py

@@ -4,7 +4,7 @@ Course API Serializers.  Representing course catalog data
 
 from rest_framework import serializers
 
-from lms.djangoapps.course_home_api.progress.v1.serializers import CertificateDataSerializer
+from lms.djangoapps.course_home_api.progress.serializers import CertificateDataSerializer
 from openedx.core.lib.api.fields import AbsoluteURLField