* disable xsslint

* fix quality errors

* disable xsslint

Remove py2 requirements.

Fixing test failure due to 31-dec-2020 date issue

Reverts two PRs:
* "Fix hiding of completion/bookmark indicators in legacy courseware (#25919)"
* "Fix hint show" (#25930)

TNL-7845

The user_tasks app is used by Studio import/export and not used by
anything in the LMS. But because our app-permissions user/role
provisioning script invokes the LMS process, any app+permission
listed there must exist in the LMS or the provisioning fails. So
this commit adds the user_tasks app to the LMS list of installed
apps because it's a lot faster than getting app-permissions to do
the right thing.

Upgrade python requirements.

Fix hint show 

fixes quality

MST-400 Update the support verification_api to provide the correct status under the same API used by learner (#25917)

Python Requirements Update

* Commits:
  Add get-accessor helper for discussions plugins
  Add is_enabled helper for discussions plugins

In the edx.org-next theme, the completion green check-
marks and the little bookmark icons were appearing on every
single unit. This was because a fontawesome CSS rule
in the new theme was overriding the `display: none`,
as set by `.is-hidden`, to be `display: inline: block`.

The fix is to add `!important` to a couple definitions
of `.is-hidden`. Definitely somewhat hacky, but this is
SCSS that we plan to deprecate at some point anyway.

TNL-7823

We seperated base and py35 as a part of the upgrade to python 3 so
that we could get newer versions of some requirements during that
upgrade.  This change is the first step in removing the old requirements
files that were only relevant to python 2.

We leave the python version centric named files instead of base because
we'll need to bump the version of this file regularly and clearly
indicating what version of python it's for makes it easier to reason
about.

Sets default X-Frame-Options for login and registration forms to environment setting

Commit 7f59688f attempted to solve this using
`CourseOverview.course_exists`, but that check is case-
insensitive. This commit instead does a small refactor
to `lms.djangoapps.courseware.get_course` so that we can
handle a failed course lookup without broadly catching
a `ValueError`.

fixed quality issues

added comment

updated for comments

fixing test

removed typo

readded files

moved settings override

testing adding other keys

not overriding setting

Merge pull request #25916 from edx/testeng/bokchoy_auto_cache_update_322bb08cae4168425cd5fa8cc3dea360e9e868c9

Bokchoy Testing DB Cache update

Python Requirements Update

* Commits:
  Implement a new configuration system for discussions plugins

Additional details available in the attached decisions document.

Co-authored-by: Kshitij Sobti <kshitij@sobti.in>
Co-authored-by: stvn <stvn@mit.edu>

Anonymous users (like crawlers) requesting non-existent courses
should get 403, just like logged-in users do. They instead raised
a ValueError.

Revert "Added endpoint to retrieve IDV photo urls"

This reverts commit 356f1875.