May improve performance.
TNL-3538

There's a lot of useful things in PR #8271 that provide a framework
for the comprehensive theming system. If we need to remove the edx.org
theme from the codebase, we can leave most of PR #8271 in, to make it
easier to build on top of and get this feature back in.

There's a lot of useful things in PR #8271 that provide a framework
for the comprehensive theming system. If we need to remove the edx.org
theme from the codebase, we can leave most of PR #8271 in, to make it
easier to build on top of and get this feature back in.

We also need to ensure that this tag is presented when loading xblocks
via the mobile app anyway. Since we're fine just giving responsive
content to everyone we don't need this check any more.

JIRA: https://openedx.atlassian.net/browse/MA-960?filter=13805

This is a squash of 38 commits ending with
5b080f979d692804452400ac5bed9b17c50b001e

use blank header_extra template instead of if statement

TNL-2487

The old code would compute the language direction once when the template
was loaded.

TNL-2269

Serve branded footer JSON/HTML/CSS/JS from an API endpoint
in the branding app.  Refactor OpenEdX and EdX.org footer templates
to use the Python version of the API, ensuring that the API
values are consistent with the footer included in main.html.

Detailed changes:

* Added footer API end-point to the branding app.
* Footer API allows the language to be set with querystring parameters.
* Footer API allows showing/hiding of the OpenEdX logo using querystring parameters.
* Deprecate ENABLE_FOOTER_V3 in favor of the branding API configuration flag.
* Move no referrer script into main.html from the edx footer template.
* Rename rwd_header_footer.js to rwd_header.js
* Cache API responses.

Authors:
Awais Qureshi, Aamir Khan, Will Daly

ECOM-1547 created new template and Sass file for new footer. Wrapped it in a feature flag and updated previously named footer-edx-new.html to footer-edx-v2.html to better track/name updates to the footer going forward.
ECOM-1547 removed data-updated attributes from body
ECOM-1548 added JS file that inits analytics event listener and makes ajax call to API to get footer and HTML and add it to the DOM
ECOM-1547 code review cleanup
ECOM-1547 rebase and Sass appraoch update after @talbs the IE9 killer slayed the mighty beast.
ECOM-1547 updated file names and added comments in light of @talbs review of PR
ECOM-1547 update to social media link styles and nav link order
ECOM-1547 updated SOCIAL_MEDIA_FOOTER_NAMES if ENABLE_FOOTER_V3 is true
ECOM-1547 added translations to screenreader text
ECOM-1547 fixed test and renamed files in line with @talbs's pending PR
ECOM-1547 cleaned up file naming

* to reflect support for IE10 and above
* to only flag IE9 (for emergency's sake) with specific html class attrs
* to remove HTML5 shiv that's not needed for IE10 and above

Add querystring param "course_mode" to the login/registration
page so the user can skip track selection.

This supports upcoming changes to the course details page
that allow the user to choose the track when clicking
"enroll", which will replace the functionality of the track
selection page.

Update <nav> elements to correctly group links
for screen readers.

Fix RTL display issue with responsive header
on the login/registration page.

This reverts commit b8184d18.

[second attempt which addresses bug building Studio]

This reverts commit 1d6fceda.

Respond to review comments:

- Rename build and config files for consistency between lms/studio.
- Fix merge conflicts with lms require config.
- Devstack uses optimized pipeline to skip require JS optimizer step
- Add tests for render_require_js_path_overrides

Co-Authored-By: Jean-Michel Claus <jmc@edx.org>
Co-Authored-By: Brian Talbot <btalbot@edx.org>
Co-Authored-By: Tim Babych <tim@edx.org>
Co-Authored-By: Oleg Marshev <oleg@edx.org>
Co-Authored-By: Chris Rodriguez <crodriguez@edx.org>