Provide 404 response on RESTified endpoints if response is empty

### Is your proposal related to a problem?

RESTified endpoints currently return 200 for every response in a manner congruent with the GraphQL specification rather than following REST rules which would preordain a 4xx response

### Describe the solution you'd like

When an empty response is returned from Hasura via a RESTified endpoint, I would like it to return 404

This could be placed behind a feature flag or environment variable or made user configurable. This will help data access requests via Hasura and REST to align to expectations of API consumers

The issue names RESTified endpoints but no files, tests, or entry points. Start by locating the RESTified endpoint response path and existing tests for empty responses, then confirm how those responses are currently classified. Done means the intended empty-response behavior is covered by tests and the configuration choice is documented.

Written by the indexing model from the issue text.