Add logging for settings update

[alexsanford]

Closes #2645

See the issue for the event description. Note that the view property names have been changed to match the section slugs, and the values in settings are comma-separated.

This PR also adds a helper class for testing logged events.

Testing Instructions

• Change some Sensei settings in a few different sections and save.
• Ensure that one event is logged for each section with changed settings.
• Ensure that the view and settings properties have the correct values based on the settings that were changed.

[jom]

Few super minor issues, otherwise looks good and works well.

[alexsanford]

Thanks, @jom! Seems the CI stuff didn't run, which would have caught those linter issues. I got it all to be green now 👍

@donnapep Could you take a look at this one before we merge?

[donnapep]

When changing the checkbox settings under Email Notifications, I only get 3 distinct settings being logged - email_learners, email_teachers, email_global. There's no way to differentiate between the different settings within each of those groups.

[alexsanford]

@donnapep Good catch on that one. This proved to be a bit tricky. In every other case when a setting changes, we want only to log the setting field name. However, for the checkboxes, the setting is stored as an array of strings, where each string is the name of the individual checkbox that was checked.

I added some code to handle this case (along with tests). It seems to work well, but please do re-test.

Also @jom I've re-requested your review because I would like you to take a look at the new code if you have a chance (944c500). It is functional, but I'm a bit worried about the readability. Would appreciate your input 🙂

[donnapep]

@alexsanford Thanks! This is what I'm seeing logged now:

Is it possible to drop the email_learners, email_teachers and email_global arrays and just log the key (e.g. learner-graded-quiz, teacher-quiz-submitted etc.)? There are also a few extraneous empty arrays being logged that don't map to a setting (email_learners[], email_teachers[], email_global[]).

[alexsanford]

@donnapep This should be fixed now 👍

[donnapep]

All good now!