AA-177: Add masquerading for course home MFE

- Looks at masquerading config for dates, outline, metadata, and
  celebration APIs in course_home_api / courseware_api.
- Consolidates and cleans up places we check whether masquerading
  gives us full access to a course.

lms/djangoapps/mobile_api/users/serializers.py

@@ -96,7 +96,7 @@ class CourseEnrollmentSerializer(serializers.ModelSerializer):
         """
         Returns expiration date for a course audit expiration, if any or null
         """
-        if not CourseDurationLimitConfig.enabled_for_enrollment(user=model.user, course_key=model.course.id):
+        if not CourseDurationLimitConfig.enabled_for_enrollment(model.user, model.course):
             return None
 
         return get_user_course_expiration_date(model.user, model.course)

lms/djangoapps/mobile_api/users/tests.py

@@ -290,7 +290,8 @@ class TestUserEnrollmentApi(UrlResetMixin, MobileAPITestCase, MobileAuthUserTest
             course = CourseFactory.create(start=self.LAST_WEEK, mobile_available=True)
             self.enroll(course.id)
 
-        add_course_mode(course, upgrade_deadline_expired=False)
+        add_course_mode(course, mode_slug=CourseMode.AUDIT)
+        add_course_mode(course)
 
     def _get_enrollment_data(self, api_version, expired):
         self.login()