* 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-3281

TNL-3202

TNL-3014

Add tests for search

Add text_search to TeamsListView

Add reindex command line tool for course teams

Add Search Pagination and update comments

Move paginate_search_results to common library

Adds a read-only mode to the discussion module which disables any
controls for updating the discussion (votes, follows, replies,
etc). This mode is enabled for users who are not a member of the team,
and are also not moderators, admins, or community TAs.

Authors:
  - Daniel Friedman
  - Ben McMorran
  - Peter Fogg

TNL-1892

The comments service rejects whitespace-only content for certain
strings, so the discussion API should also reject such content.

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

XCOM-193

This is done via PATCH on a thread instance endpoint.

Also, fix the field-specific error format for all API endpoints.

This requires cs_comments_service commit fdf017c918.

This is an initial implementation that only allows retrieval of all
threads for a course and only returns an easily computed subset of the
fields that are needed, in order to keep this change from getting too
large.

JIRA: MA-641

This is the first stage of the new Discussion API.

JIRA: MA-604

TNL-1537

Co-Authored-By: Andy Armstrong <andya@edx.org>
Co-Authored-By: cahrens <christina@edx.org>

TNL-1493

See https://openedx.atlassian.net/wiki/display/TNL/User+API for details

XCOM-107