TNL-4906 Subsections now use radio buttons, to allow for "hide after due" as a
visibility option. Also, all tabs have been consolidated to "Basic" and
"Advanced", and visibility options have moved there.

Documentation links are updated to assist course authors with the new
visibility options. Tests have also been updated, and the changes suggested
in TNL-4951 are included.

TNL-4366
Changes in studio to allow the hide_after_due setting to be utilized.

Includes:
    -python changes to contentstore, where the data is stored.
    -refactoring of timed-examination-preference-editor.underscore, to add this
        setting and make the editor more accessible.
    -javascript changes to link the new setting to the correct data model.
    -sass updates to fix a11y issues on the editor modal.
    -addition of post-due visibility information to course outline in studio.
    -new tests: python, js, acceptance, and a11y

TNL-4366
Changes in studio to allow the hide_after_due setting to be utilized.

Includes:
    -python changes to contentstore, where the data is stored.
    -refactoring of timed-examination-preference-editor.underscore, to add this
        setting and make the editor more accessible.
    -javascript changes to link the new setting to the correct data model.
    -sass updates to fix a11y issues on the editor modal.
    -addition of post-due visibility information to course outline in studio.
    -new tests: python, js, acceptance, and a11y

- added the new field review_rules for software secure
- added a new tab name "Additional Settings" for the proctored/timed exams