fix: wrong start date is displayed in susbection modal

feat: reimagine certificate display settings

The course settings `certificate_available_date` (CAD) and
`certificates_display_behavior` (CDB) were previously
acting indedependantly of one another. They now work in
tandem. This change:
- limits CDB to a dropdown
- removes "early_with_info" and adds "end_with_date"
- only takes CAD into account if "end_with_date" is selected
- Moves CDB to the main course schedule settings page
- updates CourseOverview model and CourseDetails objects to
validate these fields and choose sane defaults if they aren't
expected values

This work was previously done in bd9e7dd (complete with bugs), so this
version is toggleable via the ENABLE_V2_CERT_DISPLAY_SETTINGS setting

Formerly, bulk management was enabled by sending feature feature
toggle to Gradebook which also checked for the presence of a 
master's track to enable the feature. This default enables for all
courses with a master's track and also allows selective enabling 
for courses with the feature flag.

MICROBA-1410

chore: Removed constraint on django-countries

chore: Django3 has removed python_2_unicode_compatible.

Translate prerequisite section banner text

fix: wrong start date is displayed in susbection modal with xblock's start date so use course context's start date (AA-945)

Execute the codemodes.

feat: enable effort estimation feature by default

fix: display relative due date on limited time assignments (AA-943)

This model has been replaced by the CertificateAllowlist.

MICROBA-1304

chore: Django3 has removed python_2_unicode_compatible.

* feat: Celery tasks instead of synchronous emails for enrollment, in notify_enrolled_learners()

ENT-4779

ENT-4779

* feat: use edx-enterprise 3.27.11 for improved error handling in email notify task

With Badgr v2 API, notification emails for earning badges are
no longer sent to learners by default. However, the request to
create a badge assertion accepts an optional boolean property
"notify", that can be used to enable/disable email notifications.

Make it configurable by an optional setting `BADGR_ENABLE_NOTIFICATIONS`
(defaults to False).

[OSPR-5796] [BB-2862] "LANGUAGE_CODE" site configuration option

disable subframe dialog suppression for sites which use ENV_TOKENS for config.

feat: log event for custom pacing when user submits relative date for self paced course (AA-921)

This model has been replaced by the CertificateAllowlist.

MICROBA-1304

Execute the codemodes.

Execute the codemodes.

This Pr updates the features list of the discussion providers for,
1. Combines LTI basic configuration and LTI integration into 1 feature.
2.Enables Primary discussion app experience for Yellowdig
3. Hides Automatic learner enrollment from this list

FE changes (in Other PR):
1. Turn edX to Full Support instead of partial support
2. Rename Partial support to Basic support

https://openedx.atlassian.net/browse/TNL-8546

chore: Django3 has removed python_2_unicode_compatible.

refactor!: Remove unused callback endpoints used for PDF cert generation/updates

This reverts commit f380dffe.

to delegate access to BTR maintainers on Named Release branches.

for Chrome version 92. This token is added to the courseware iFrame, which
enables the iFrame to retain the ability to summon modals & alerts - or open
new windows via JS. This token has a limited lifespan - it currently expires around
Dec 14, 2021.

TNL-8559

[MICROBA-1087]
[DEPR-155]

* Removed callback functions that were originally used to update certificates (and example certificates) post xqueue processing

chore: update edx-enterprise to 3.27.9

We control rollout of the Learning Sequences REST API with the
USE_FOR_OUTLINES (learning_sequences.use_for_outlines) course waffle
flag. But sometimes we're going to want to be able to take a look at
production data output of this API before explicitly turning the API on
(and switching over to it) for the Courseware MFE. To do this, we're
going to make the availability base itself purely on the waffle flag and
course type (Old Mongo courses are not supported), and allow people to
"peek" at what the API would have given if it was rolled out by passing
an explicit "force_on=1" querystring param.

This is work to support the rollout of TNL-8330.

Execute the codemodes.