Demonstrate that we can provide access to one RPC-style action API endpoint via a route registered in a module definition file and routed via the REST framework.
Goals:
- the code of the action API module should not need to be changed (but we may add glue code / mapping declarations / schema definitions)
- the endpoint is defined in a module definition file
- we can generate an OpenAPI spec for the endpoint, including a response body schema
- parameter validation and error representations follow the conventions of the REST API