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/course_api/tests/test_views.py

@@ -395,7 +395,7 @@ class CourseListSearchViewTest(CourseApiTestViewMixin, ModuleStoreTestCase, Sear
         self.setup_user(self.audit_user)
 
         # These query counts were found empirically
-        query_counts = [62, 45, 45, 45, 45, 45, 45, 45, 45, 45, 15]
+        query_counts = [53, 45, 45, 45, 45, 45, 45, 45, 45, 45, 15]
         ordered_course_ids = sorted([str(cid) for cid in (course_ids + [c.id for c in self.courses])])
 
         self.clear_caches()