More accurately, this creates a 4th shard because the
last shard is always the default.

Revert "SUST-35 Implementation of course_key_from_string_or_404 to return course_key or raise a 404"

-Adressed all comments

-Updated method "course_key_from_string_or_404" to raise message too.
-Wrote tests for "course_key_from_string_or_404" when exception message is given.
-Modified existing methods to use "ddt.data".
-Used Splunk logs to find exectly where we were getting "Invalid Key Error"
-Updated Views where we were getting "Invalid Key Error" in splunk logs.
-Wrote tests for those View End points where we were getting "Invalid Key Error"

TEST_DATA_MIXED_MODULESTORE
Remove these test mixed modulestores:
TEST_DATA_MIXED_TOY_MODULESTORE
TEST_DATA_MIXED_CLOSED_MODULESTORE
TEST_DATA_MIXED_GRADED_MODULESTORE

Prevents start date alone from being used to filter out categories in self-paced courses during construction of the category map. ECOM-4017.

Prevents start date alone from being used to filter out categories in self-paced courses during construction of the category map. ECOM-4017.

TNL-4284

This will leverage the nose attrib plugin to allow us
to break tests apart on our build system to run
in parallel on separate nodes.

Also accelerates forums UnicodeTestCases

CCX REST APIs
OAUTH2 authorization for CCX APIs
- oauth2 authorization required for ccx list.
- Course-instructor permission for ccx api endpoint
- Protection for detail view too.

Tests for CCX REST APIs and OAUTH2 authorization

There are 3 main changes in this commit:
* CohortFactory now sets up memberships properly, so consuming tests do not
need to explicitly touch CourseUserGroup.users to add() users.
* test_get_cohort_sql_queries has been updated to 3 and 9 queries when using
and not using the cache, respectively. This is needed due to each operation
needing an extra queery to get the CourseUserGroup from the CohortMembership.
* Adding remove_user_from_cohort(), the counterpart to add_user_to_cohort().
This is also to keep tests from touching the users field directly, and keep
CohortMembership data in sync.

The preferred form is to use CourseKey.from_string() instead of
SlashSeparatedCourseKey.from_deprecated_string().

Please note that this is a squshed commit and the work of:
Symbolist, macdiesel, nedbat, doctoryes, muzaffaryousaf and muhammad-ammar

Also remove useless docstrings where they were added to keep pylint
quiet.

* Fix paver violations to stablize edx-lint update
* Parens, Line2Long
* Fix missing docstrings
* Fix PEP8 issues
* Address PR feedback (thanks @nedbat!)

* 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)

* 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)

TNL-3179

TNL-3196

Some low hanging fruit optimization of forums tests.

These signals are caught by the Teams app and used to update
`last_activity_at` on both teams and individual users.

TNL-2497