This specifically enables/disables the underlying comment service client
used to make calls to the service.  When disabled, this client will now
throw an exception which can be propagated upwards so that callers can
make the right decision about how to notify users of the error, or
handle retry, etc etc.

- Default of "desc" is all that is in use, and remains as-is.
- Discussion API keeps order_direction param, to minimize changes,
but it only accepts "desc".
- Discussion webapp simply no longer sends in the sort order.

- Default to with_responses=False, except when required.
- Clean up search call unused params.

We're often grabbing the metadata of a specific thread to then be able
to perform other operations, but we never need the actual responses or
comments of a thread unless we're displaying it in the normal forum
view.

This change sets a default of with_responses=False, which instructs the
comment service to not send back the responses/comments for the given
thread.  We only ask for responses in the case of rendering a single
thread or inline discussion.

* Renames discussion_module to discussion_xblock
* Moves common/lib/xmodule/xmodule_discussion to openedx/core/lib/xblock_builtin/xblock_discussion

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.

* 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)

MA-1212 - added response count field in tests

removed unneccessary function

"MA-1212 - added response count in thread retrieval service and updated tests"

updated serializerz test for response count

MA-1212

exclude response count from thread get list

removed response_count field from update and create thread services

made resp_total dynamic for cs thread in test_serielizer

quality fixed

improved quality

add TODO JIRA ticket on removed fields

An incorrect response was being returned when voting for a comment
or thread.

MA-1182 - added test for not enrolled in course, removed commented out nose test code, formatted import statements according to edx standards

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

TNL-2497

Currently when GETting comments, the thread of the comment will be
marked as read. This change makes this effect optional as well as
setting the default to not mark the thread as read.