- Remove usage of django.urls.patterns
- Change urls tuples to lists
- Make all string view names callables

Moves ENABLE_ENTERPRISE_INTEGRATION to settings.FEATURES,
and changes the default value to False.

ENT-624

ENT-624

Since we have a separate call to grant consent, we shouldn't try to set that value on
the enterprise course enrollment anymore, because it causes errors.

This incorporates a migration that copies data
from certain models to another.

LEARNER-1523
LEARNER-1524

Enrollment attributes are now always stored, regardless of whether an enrollment is being created or updated. This will ensure that learners who purchase paid modes, without first enrolling in a non-paid mode, can request refunds if they choose to un-enroll from a course run within the refund window.

LEARNER-1282

LEARNER-394

ECOM-7099

There are a number of Django Signals that are on the modulestore's
SignalHandler class, such as SignalHandler.course_published. These
signals can trigger very expensive processes to occur, such as course
overview or block structures generation. Most of the time, the test
author doesn't care about these side-effects.

This commit does a few things:

* Converts the signals on SignalHandler to be instances of a new
  SwitchedSignal class, that allows signal sending to be disabled.

* Creates a SignalIsolationMixin helper similar in spirit to the
  CacheIsolationMixin, and adds it to the ModuleStoreIsolationMixin
  (and thus to ModuleStoreTestCase and SharedModuleStoreTestCase).

* Converts our various tests to use this new mechanism. In some cases,
  this means adjusting query counts downwards because they no longer
  have to account for publishing listener actions.

Modulestore generated signals are now muted by default during test runs.
Calls to send() them will result in no-ops. You can choose to enable
specific signals for a given subclass of ModuleStoreTestCase or
SharedModuleStoreTestCase by specifying an ENABLED_SIGNALS class
attribute, like the following example:

    from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase

    class MyPublishTestCase(ModuleStoreTestCase):
        ENABLED_SIGNALS = ['course_published', 'pre_publish']

You should take great care when disabling signals outside of a
ModuleStoreTestCase or SharedModuleStoreTestCase, since they can leak
out into other tests. Be sure to always clean up, and never disable
signals outside of testing. Because signals are essentially process
globals, it can have a lot of unpleasant side-effects if we start
mucking around with them during live requests.

Overall, this change has cut the total test execution time for
edx-platform by a bit over a third, though we still spend a lot in
pre-test setup during our test builds.

[PERF-413]

Hackathon XV project

ECOM-5936

ECOM-4763

This reverts commit 21746f1e.

ECOM-4763