[sneridagh]

Part of #269, for the Volto port (phase 9). Stacked on #350.

The plone.restapi side of the content types driver moves from @plone/cmsui into @plone/controlpanels, so Aurora and Volto share it. Aurora runs it on the server, and Volto will run it in the browser.

@plone/controlpanels

• createRestApiDriver(request, backend): the content types driver for plone.restapi. It uses @content-types, @behaviors and @workflows (Endpoints for per-type content settings, behavior order and workflow assignment plone.restapi#2061) when backend says the site has them, and @controlpanels/dexterity-types otherwise, with those capabilities off. Workflow changes finish while the request waits, so the driver returns jobs that are already done.
• detectRestApi(request): which of those services the backend has. A 404 means it's missing. An unclear answer, such as a 401, is marked so the app doesn't keep it.
• RestApiRequest: each app passes its own function to call plone.restapi, with its credentials. It resolves with the response's body, and rejects with the status and the body, as @plone/client and Volto's Api do.
• The payload translations moved here from cmsui, under src/content-types/restapi/: dexterityTypes.ts (was helpers/contentTypes.ts) and contentTypesService.ts (was helpers/contentTypesApi.ts), with their tests. errorMessage also reads response.body.

Aurora (@plone/cmsui)

• helpers/contentTypesBackend.ts: restApiRequest(cli) adapts @plone/client, and contentTypesDriver(cli) builds the driver for the backend. What a backend has is still kept for a minute.
• routes/api/contentTypes.tsx is a thin layer over the driver: each route calls one of its methods. It adds @workflow-assignments, and POST @workflow-changes (with ?preview for the dry run).
• auroraDriver.ts is a thin client for those routes.

No behavior changes.

Checks

• Unit tests: @plone/controlpanels has 121, including the new driver's tests; @plone/cmsui has 434. check:ts and lint pass.
• Acceptance, content-types.test.ts on both backends:
  • Released plone.restapi: 19 passed, 6 skipped.
  • plone.restapi issue-2061-workflows (Add @workflows and changing a type's workflow (#2061 step 4) plone.restapi#2081): 22 passed, 2 skipped. "reorders custom fields with the keyboard" failed once; its cause is fixed in Add the Fields tab to the content type page #313.
• In Volto, the same driver runs in the browser with Volto's Api (the coming plone/volto PR).

See #269 for how to review and merge the stack.