The main changes are:
- Kind, Href, Id fields for every object returned
- Attach operationIds to each request, return it for errors
- Errors are predefined and queryable
Instead of sending a `token` to workers, send back to URLs:
1. "location": URL at which the job can be inspected (GET) and updated
(PATCH).
2. "artifact_location": URL at which artifacts should be uploaded to.
The actual URLs remain the same, but a client does not need to stitch
them together manually (except appending the artifact's name).
Unfortunately, the client code generated by `deepmap` does not lend
itself to this style of APIs. Use standard http.Client again, which is a
partial revert of 0962fbd30.
Write an openapi spec for the worker API and use `deepmap/oapi-codegen`
to generate scaffolding for the server-side using the `labstack/echo`
server.
Incidentally, echo by default returns the errors in the same format that
worker API always has:
{ "message": "..." }
The API itself is unchanged to make this change easier to understand. It
will be changed to better suit our needs in future commits.
