TNL-4366 Add ability to hide timed exam after due date

TNL-4366

This commit adds a new field, `hide_after_due` to the ProctoredExam model. This field
is intended to allow course authors to override the default setting and keep exam
results hidden from learners after the due date for the exam has passed.

Also included are migrations, tests, and api updates to allow this functionality to
be used.

fix the bug where 'Proctored Option available' appears on the left pa…

fix the bug where 'Proctored Option available' appears on the left pane for a proctored exam in an expired instructor paced course

Fix timer time difference

Pass requesting user on delete_student_attempt

The LMS implementation that will be performing this work is being changed
to require requesting user information as part of a seperate bugfix.

See TNL-4152, ARCH-18 for details.

let the student take exam without proctoring if the  exam has no due …

Afzaledx/sol 1653 course due date for self paced

update the due-date if different from context. This happens if the course has changed from instructor-paced to self-paced.

fixed the tests.

PR comments.

PR comments.

Incremented package version for 0.12.12

Fetch correct remaining seconds from proctoring

Incremented version for 0.12.11 release

PHX-250 / Emit an event for creation of attempt.

PHX-252 / Added check for practice exam when due date has passed

Ibrahimahmed443/sol 1611

Correct Django Requirement

Django 1.9a is less than 1.9 and should not be installed as a requirement.

Incrementing version for 0.12.10 release

remove newline from logging; add exam code and course ID only

PHX-244 / Added API to get the student's course completion date

fix the bug where the learner gets full time even after due date is p…

PHX-244 Increment package version

SOL-1480 Allowance Section UI changes

additional_time_granted value used as string.

Refactoring for PR comments.

Refactoring for PR comments.

PHX-224 / Added Migration for unique Attempt Code