This should make it easier to test programs-related features. Preface to ECOM-3200.

Includes a11y coverage. ECOM-3980.

When receiving an error explained in TNL-3942, I found this kind of
instrumentation to be helpful.

Extends the Programs ConfigurationModel, cleans up Programs-related utilities and corresponding tests, and corrects caching. Uses the Programs API to list programs within Studio. ECOM-2769.

Also remove useless docstrings where they were added to keep pylint
quiet.

Entrance Exam.

unit test to check presence of entrance_exam_passed

changed based on Matt's feedback

changes after Asad's feedback

TNL-3179

The old line:

    from path import path

produced pylint errors because of the baroque way that path.py defined
"path".  We tried to get them to change how they defined it, but they
deleted the name instead: https://github.com/jaraco/path.py/issues/102

(Jason then changed his mind, but this is a better way to use path.py,
it avoids the pylint error at least.)

These signals are caught by the Teams app and used to update
`last_activity_at` on both teams and individual users.

TNL-2497

some optimisations

refactored code and added created event

added test to make sure generate event is emitted

changes based on feedback on 6/11

added certificate web page and tests

fixed quality violations

TNL-1530

Conflicts:
	lms/djangoapps/courseware/courses.py
	lms/djangoapps/instructor_task/api.py

refined entrance exam student attempts reset
added rescore, delete state and task history functionality

TNL-1304

Co-Authored-By: Jean-Michel Claus <jmc@edx.org>
Co-Authored-By: Brian Talbot <btalbot@edx.org>
Co-Authored-By: Tim Babych <tim@edx.org>
Co-Authored-By: Oleg Marshev <oleg@edx.org>
Co-Authored-By: Chris Rodriguez <crodriguez@edx.org>

SOL-1, SOL-2, SOL-3

A link to show the comments appears in their place.

Each thread's type is now included in its post details, and question
threads have marked answers shown immediately below the body of the
initial post.

FOR-122

STUD-1658

FOR-545