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some dangerously outdated documentation in code that was unearthed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

TNL-3889

TNL-3465

TNL-3819

Previously, api.update_from_assessments() would call model.
update_from_assessments(), then api._serialized_with_details(reqs), which
would duplicate the update work we *just* did as part of getting the
status. Now, update() and get_details() are totally seperate operations, and
_serialized_with_details() is a read-only method that does not need to have
requirements passed in.

I've also standardized student_training and peer, the two assessment types that
do *not* auto-complete on None requirements, to return False if None, and error
out if passed {}. This is to allow staff_assess to pass None to indicate
"Update thyself, if you don't depend on requirements" to the other step types.

Also adding test_requirements_changed(), to confirm that workflows are updated
when requirements change, even though thoe requirements are no longer explicitly
passed to the getter.

Fairly simple test, should help to provide some extra peace of mind.

I misunderstood what was happening in my cursory investigation earlier -
all that needs to change here is the type of exception being caught.

TNL-3464

Add a test to verify that it is working as expected.