New "unlisted" status in Coda

[LeMurphant]

Context: https://docs.google.com/document/d/12NicU1N-ijHuM8J6gIAcp3snOZKUQ6zlguB8Cs21JIQ/edit#heading=h.bxchuroysqj9 We want a status in coda that lives between "in progress" and "live on site" that is partially discoverable.

Articles tagged as "unlisted" would

• Have a specific banner similar to "in progress"
• Be discoverable in Search
• Be linkable from inside articles
• Not show up in the tree (editors will take care of this)
• Not show up in "Related"

Articles could be changed to "unlisted" by people in the "@editor" role on discord (subject to change)

There is some uncertainty on how "unlisted" should interact with "in review". The simple option is that anything "in review" would inherit the permissions of "unlisted", but this means that we would need to clamp down on permissions to send to "in review". Another option is to make "in review" a tag instead of a status, TBD