There's still a bunch of duplicated code to create a VRS service for RESTBase/Parsoid:
Every time we make a config change (like zero-conf VE, T248343) this all needs to be updated.
We should probably make sure that something like ApiParsoidTrait is upstreamed into core for 1.36 to eliminate this redundancy.
- RESTBase is going away, maybe this VRS interface is as well? (T250500: ParserCache / RESTBase / Parsoid integration)
- The forks have grown their own unique hair -- Flow for instance deliberately bypasses restbase, and hasn't deprecated its old $wgFlowParsoidURL configuration (still used in WMF's mediawiki-config) yet, etc.