Log face match results to events.log (LG-2495)

[zachmargolis]

(Builds on previous work in #4007 and #4001 that update logging to the database)

This PR adds logging to events.log, it's stringing together a few different files so here's what's going on:

• We have Flows and Steps, and FormResponses.
• Before
  • If Step#call returns a FormResponse, we would log it
  • Our Acuant::Response objects duck-type FormResponses, but are not actually form responses so the previous check to log would fail
  • The Step#call was not returning the result object in most cases at all anyways
• After
  • We now do a duck type check that allows Acuant::Response objects to be logged (the response objects are already pretty well-behaved about PII)
  • Updates specific steps to make sure they log results (not all)
• Open Questions
  • Should we audit all steps now and make sure they log? For the purposes of this ticket and this PR, I think no, but it would probably match expectations later down the line

I also added a matcher for FakeAnalytics and to make testing this a little cleaner

[stevegsa]

Looks good!

[mitchellhenke]

👍🏼

[solipet]

LGTM!