Add a third option for captive/cultivated question (unknown or grey area)

[tiwane]

We’re working on a broader rethinking of wild/not wild and establishment means, so I’m going to close this request.

[jdmore]

Tony, did you want to go ahead and close this one too, then?
https://forum.inaturalist.org/t/add-one-but-only-one-new-establishment-means-category-uncertain/3805