The repo/rest-api/ directory becomes a central place containing the REST API documentation, shared infrastructure and e2e test helpers.
Move:
- all the PHP code and phpunit tests
- OpenAPI document
- all the e2e end and OAS tests
Don't move:
- test helpers
- OpenAPI document build step
- routes.dev.json
The README.md has to be split. Things concerning the REST API as a whole should stay in that directory. Everything specific to the domain (/the PHP code) moves into repo/domaisn/crud/README.md.
Wire up namespaces; basically https://gerrit.wikimedia.org/r/c/mediawiki/extensions/Wikibase/+/764731 but for the new directory.