Add tracking logs

[pomegranited]

Description:

This PR updates open-craft#173 to merge latest master and get tests passing again.

open-craft#173 is the first step for openedx/openedx-aspects#222

JIRA:

Private-ref: FAL-3766

Merge deadline: ASAP -- there's follow-up work to come soon.

Installation instructions:

1. Install this package in your LMS venv
2. Ensure completion is enabled : should be a waffle switch enabled for [completion.enable_completion_tracking](http://local.edly.io:8000/admin/waffle/switch/1/change/)
3. Create a course with one or two subsections, sections, blocks.

Testing instructions:

1. Watch the tracking.log file generated by your LMS for completion events, e.g tail -f $(tutor config printroot)/data/lms/logs/tracking.log | grep compl
2. Enrol in your test course and complete some blocks.
   You should see openedx.completion_aggregator.progress.* events coming through to mark the progress towards completion of the units (vertical), subsections (sequential), sections (chapter), and course.
   When you've completed the children of these blocks, you should see corresponding openedx.completion_aggregator.completion.* events.

Reviewers:

• @andrey-canon
• @Agrendalath

Merge checklist:

• All reviewers approved
• CI build is green
• Version bumped
• Changelog record added
• Documentation updated (not only docstrings)
• Commits are squashed
• PR author is listed in AUTHORS

Post merge:

• Create a tag
• Check new version is pushed to PyPI after tag-triggered build is
  finished.
• Delete working branch (if not needed anymore)

[pomegranited]

Hi @andrey-canon ! I've (finally) started looking at how best to get your changes into the completion aggregator so that Aspects users can use these events. I'm sorry it's taken me so long!

Do you have time to look at this PR in the next week or so? If not, that's totally fine -- I can resubmit it against master and get it reviewed by OpenCraft.

cf openedx/openedx-aspects#222 for the plan so far, comments are very welcome.

[pomegranited]

Closed in favour of open-craft#206