TNL-4622

Also adds improved styling for course pacing settings, and unit tests
around query counts for self-paced courses.

ECOM-2650

* Automatically create user partitions on course publish for each ICRV checkpoint.
* Disable partitions for ICRV checkpoints that have been deleted.
* Skip partitions that have been disabled when checking access.
* Add verification access control UI to visibility settings.
* Add verification access control UI to sequential and vertical settings.
* Add partition scheme for verification partition groups.
* Cache information used by verification partition scheme and invalidate the cache on update.
* Add location parameter to UserPartition so the partition scheme can find the associated checkpoint.
* Refactor GroupConfiguration to allow multiple user partitions.
* Add special messaging to ICRV for students in the honor track.

Authors: Zubair Arbi, Awais Qureshi, Aamir Khan, Will Daly

The mobile clients need the request to fail if they don't have
permisssions so that they know to refresh a session token.

JIRA: https://openedx.atlassian.net/browse/MA-1003

JIRA: https://openedx.atlassian.net/browse/MA-972

This is an initial authentication implementation that allows LTI users to
log in transparently to edX. The behavior is driven by pilot users at
Harvard; this was the most requested feature.

The patch creates a new database model that maps users' LTI identifiers
to newly-created edX accounts. If an LTI launch comes in with a user_id
field that is not in the database, a new edX account is created with a
random user name and password. This account is then stored in the
database, so that it is permanently associated with the LTI user ID.

This patch takes a simplistic approach to session management. If a user
is logged in with a different account when they perform an LTI launch,
they will be logged out and then re-logged in using their LTI account.

In order to keep the patch simple, I have split out some refactoring
that needs to be done into a separate branch that I'll post once this
has been merged. Since we no longer redirect to the login page, we don't
need to maintain two separate LTI endpoints (one for the LTI launch and
one for authenticated users), or deal with the session management that
requires. There are also multiple fetches of the LtiConsumer object
(one in the view, one in the signature validation) that the later
patch will consolidate into one.

This branch fixes the previous conflicts with the test refactoring
carried out in PR 8240.

Change https://github.com/edx/edx-platform/pull/8240 refactored the LTI
provider template rendering code and introduced an issue where a user was
required to be enrolled in a course before that course's content could be
accessed over LTI. According to the LTI design spec:
    https://docs.google.com/document/d/185hdPvIxcKtiDOLjb4sTGovA_WYXWz5Cd79gCzQwBms
we delegate access control over LTI content to the LTI consumer, rather
than requiring that users enroll in edX courses explicitly (and that admins
keep edX and LTI provider enrollemnts consistent when students add or drop
courses).

This change fixes the immediate issue, which is disrupting the LTI Provider
pilot currently running at Harvard.