* Remove authentication, including SessionAuthentication, to fix CSRF
exemption by dropping CSRF check of SessionAuthentication.
* Several changes to make it more clear that only POST is supported and
clean up GET method testing.
* Removed the temporary 403 error logging that wasn't working.
* Removed test_single_access_token which was written for DOP, but
doesn't work with DOT. See
[MA-2122](https://openedx.atlassian.net/browse/MA-2122) for a ticket
about implementing this for DOT, although it doesn't seem to be a
priority. NOTE: A comment was added to the ticket explaining that this
test was removed.
* GET now returns default error for methods not allowed.
ARCHBOM-1667
* Generate common/djangoapps import shims for LMS
* Generate common/djangoapps import shims for Studio
* Stop appending project root to sys.path
* Stop appending common/djangoapps to sys.path
* Import from common.djangoapps.course_action_state instead of course_action_state
* Import from common.djangoapps.course_modes instead of course_modes
* Import from common.djangoapps.database_fixups instead of database_fixups
* Import from common.djangoapps.edxmako instead of edxmako
* Import from common.djangoapps.entitlements instead of entitlements
* Import from common.djangoapps.pipline_mako instead of pipeline_mako
* Import from common.djangoapps.static_replace instead of static_replace
* Import from common.djangoapps.student instead of student
* Import from common.djangoapps.terrain instead of terrain
* Import from common.djangoapps.third_party_auth instead of third_party_auth
* Import from common.djangoapps.track instead of track
* Import from common.djangoapps.util instead of util
* Import from common.djangoapps.xblock_django instead of xblock_django
* Add empty common/djangoapps/__init__.py to fix pytest collection
* Fix pylint formatting violations
* Exclude import_shims/ directory tree from linting
* Remove ThirdPartyAuthProviderApiPermission
Also removed ProviderApiPermissions and ApiPermissionsAdminForm and removal of DOP for third_party_auth
* Removing model
* Replaced long_token with default_token_generator
* Adding skip to test_migrations_are_in_sync
PSA was monolothic, now split, with new features, like
a DB-backed partial pipeline. FB OAuth2 version also upped.
Partial pipelines don't get cleared except when necessary.
They persist for special cases like change of browser while
still mid-pipeline (i.e. email validation step).
Refactor, cleanup, and update of a lot of small things as well.
PLEASE NOTE the new `social_auth_partial` table.
Available backends:
* django-oauth-toolkit (DOT)
* django-oauth2-provider (DOP)
* Use provided client ID to select backend for
* AccessToken requests
* third party auth-token exchange
* Create adapters to isolate library-dependent functionality
* Handle django-oauth-toolkit tokens in edX DRF authenticator class
MA-1998
MA-2000
