Editor Assessments Order improvements

Now setting self.editor_assessments_order whenever we correct it for
template rendering, and modifying the logic to be more careful with
how assessments types not-specified-by-the-user are presented so
that they remain in the default, legal order.

Improve text strings

Changing wording of "waiting for peers" message.

Be robust to username not being available.

TNL-4019

TNL-4018

TNL-4027

Render Incomplete simplification

Simplfying logic for display strings in all "user action needed" states.

Fixing up oa_response

With staff now being a possibility, we need to update oa_response_complete.
Now keeping "Needs to be graded" and "You need to do things" separate. Includes
test fixes.

Staff can view uploaded files

Emulating the approach used by peer_mixin to allow staff to actually
see uploaded files. Also updates oa_student_info to make use of
oa_uploaded_file.html instead of duplicating that logic. Test
updates also included.

i18n fixes

Properly translate strings *before* passing as variable

Move focus within staff panels.

TNL-3932

Make checkboxes accessible.

TNL-3999

The crux of this fix is that scored_only behavior in various api/peer.py
methods is no longer needed, or correct. This value has been removed, so
that assessments may be gotten (and medians found) when the assessments
are not used in determining the final score (say, if a staff score exists).

Also includes updates to the "waiting for steps" string as prescribed by
@catong in https://github.com/edx/edx-ora2/pull/764, along with logic for
that method, and updates to tests and get_wating_details logic in light
of this simplification.

TNL-3958

The refresh model in the staff grading form changed.
Also add a "scrollToTop" call when continuing grading.

TNL-3870

Full staff grading UI

Includes fixing my previous work on the staff assessment test to
use the required flow, not the override. Also refactors full workflow
tests and adds a new one to include a required staff grading step.

Part 2 (TNL-3493)

TNL-3493

Minor doc tweak

Per offline conversation with @catong, changing some wording in the
user visible string for editing ORA assessment steps.

Doc updates staff grading in Studio

Updating a user-facing string to include staff grading. Also updating
some dangerously outdated documentation in code that was unearthed
during PR review.

Able to enable full staff grading from studio, save without errors, and view
the staff grading step as expected from LMS.

Includes:
    -template additions, staff grading disabled by default
    -fetching real staff requirements
    -javascript to hook into the python backend
    -changing some default assumptions about assessment types
    -modifications to validation
    -small bugfix for scroll behaviorwith validation alert.
    -updates to existing unit tests
    -additional validation, serialization, and javascript tests
    -fix for staff requirements bug (no more duble-unpacking)
    -updates the bundled studio js file
    -moving StaffWorkflow initilization to api's on_init() method
    -acceptance tests (lms)
    -addition of "Staff Assessment Section" to test course for bokchoy tests
    -renaming `requirements` to `<type>_requirements` in assessment apis