LEARNER-1375

MA-1998 Install and configure django_oauth_toolkit to coexist with
existing oauth libraries.

Cached values were leaking across tests, causing difficult to debug errors,
particularly when using Config Models. As part of this work, certain tests
that had query counts that relied on those values being cached needed to
be adjusted up.

TNL-3442

Preserve DRF v2 behavior of defaulting to None
for missing keys in the grading policy dictionary.

* Upgrade edx-submissions
* Upgrade edx-ora2
* Upgrade edx-val
* Upgrade edx-proctoring
* Update all edx-platform code that depends on DRF, including:
  - auth_exchange
  - cors_csrf
  - embargo
  - enrollment
  - util
  - commerce
  - course_structure
  - discussion_api
  - mobile_api
  - notifier_api
  - teams
  - credit
  - profile_images
  - user_api
  - lib/api (OAuth2 and pagination)

Preserve DRF v2 behavior of defaulting to None
for missing keys in the grading policy dictionary.

* Upgrade edx-submissions
* Upgrade edx-ora2
* Upgrade edx-val
* Upgrade edx-proctoring
* Update all edx-platform code that depends on DRF, including:
  - auth_exchange
  - cors_csrf
  - embargo
  - enrollment
  - util
  - commerce
  - course_structure
  - discussion_api
  - mobile_api
  - notifier_api
  - teams
  - credit
  - profile_images
  - user_api
  - lib/api (OAuth2 and pagination)

New classes for the return type, and changes to the has_access function and tests to make them compatible.

Display warning message on course outline in Studio when course contains deprecated features/components

TNL-2303

IsAuthenticatedOrDebug hides potential issues with API client code that is run in local environments and later deployed to production where authentication fails.

XCOM-193

* Handle grading errors

TNL-1988

API Layer.

Celery requires all tasks to be in a tasks module. Also, the task has been updated to use default values if the the course structure generator encounters a block without the graded or format fields.

CourseLocator is not JSON-serializable. Passing course keys as Unicode instead when scheduling tasks to update course structure.

Sorting on unicode value of course ID since CourseLocator objects cannot be compared to SlashSeparatedCourseKey objects.

Updated filter to ensure only course descriptors are returned.