R1:03ab7224bb4e

Reduce STATUS_CLOSED (now internally "Published") revision status callsites

Summary:
Ref T2543. Add `isPublished()` to mean: exactly the status 'closed', which is now interally called 'published', but still shown as 'closed' to users.

We have some callsites which are about "exactly that status", vs "any 'closed' status", e.g. including "abandoned".

This also introduces `isChangePlanned()`, which felt less awkward than `isChangesPlanned()` but more consistent than `hasChangesPlanned()` or…