* Initial statement of intent regarding Listings
I want to use this pull request as a means of conveying intended
direction; namely that we want Forem administrators to be able to toggle
off (or on) the Listing feature set.
This refactor is a first, yet incomplete pass, that doesn't make the
code worse. Expect more of a similar vein as we work to put the Listing
feature set behind a feature flag.
Related https://github.com/forem/rfcs/issues/291
* Adding feature flag based on reviewer comment
77d9640e3e