mentoring-opaque-keys: Adds support for opaque keys

Skip brittle HTML editor lettuce test

Updates commit hash to add support for opaque keys in mentoring. See
https://github.com/gsehub/xblock-mentoring/pull/2 for the relevant
commits.

Flaky for Bok-Choy Video Tests

Update index file; change link in PA for Students

New Open edX Install/Operations doc

Modified description of transcript bug fix

As well as updated the index page for usability

doc-389

This fixes a few accessibility problems with drag and drop

i18n: Make checklists translatable

Ahodges/documentation/doc156

Benpatterson/disable course export acc test

Adaptive hint correct_answer must be lc

Ahodges/documentation/doc368

Now the description & action_text strings in checklists can be extracted and translated.

create draft request gets already created version if it exists

Fixed register button on edge homepage.

LMS-2719

Switch quality tasks to paver

Sylvia/docs/tim 243

Allow creation of components on container page

This commit implements STUD-1490, allowing creation of components
on the container page. It also enables the delete and duplicate
buttons now that new content can be created that would benefit.

Note that it also creates shared functionality for adding components,
and refactors the unit page to use it too.

Extended Embargo feature to support site access restriction and ip network

Release

Added totals for different student tracks

Tolerance expressed in percentage now computes correctly. [BLD-522]