Two new certificate statuses are introduced, 'audit_passing' and
'audit_notpassing'. These signal that the GeneratedCertificate is not
to be displayed as a cert to the user, and that they either passed or
did not. This allows us to retain existing grading logic, as well as
maintaining correctness in analytics and reporting.

Ineligible certificates are hidden by using the
`eligible_certificates` manager on GeneratedCertificate. Some places
in the coe (largely reporting, analytics, and management commands) use
the default `objects` manager, since they need access to all
certificates.

ECOM-3040
ECOM-3515

This reverts commit 60860e3a.

An `eligible_for_certificate` field is added to the
GeneratedCertificate model. This way we can retain existing grading
logic, as well as maintaining correctness in analytics and reporting.

Ineligible certificates are hidden by using the
`eligible_certificates` manager on GeneratedCertificate. Some places
in the coe (largely reporting, analytics, and management commands) use
the default `objects` manager, since they need access to all
certificates.

This commit also updates the DB cache for acceptance tests.

added unit test to test certs exception same user different courses scenario

Also added reset_test_case() and @modifies_courseware to SharedModuleStoreTestCase.

Revert "More verbose test builds in Jenkins, for debugging."

This reverts commit 58cade4cc4288335026649470a48b7bbca969ee8.

Enable Student-Generated Certificates for HTML certs flow

* added generate certificates task and bok choy tests
* added unit tests
* changes based feedback and improved acceptance test
* Change header text
* changes based on feedback on 24/6
* added task_id to api output
* fixed broken test
* Remove "Instructor" from strings, per Docs team
* Fixed flaky entrance exam test

Allow global staff to generate example certificates
on the instructor dashboard.

Allow global staff to enable/disable self-generated
certificates for a course.