coserv: Implement coserv-well-known-info

[DhanusML]

Implement the discovery document spec for CoSERV HTTP endpoints (section 6.1.1 of draft-ietf-rats-coserv-05).

[thomas-fossati]

I am wondering if this capability should instead live in veraison/apiclient since it’s a CoSERV API object rather than a CoSERV data model object.

[DhanusML]

I was thinking the same, but raised the issue here because

1. Both the server and client consume this structure
2. All CoSERV HTTP endpoints MUST confirm to the CDDL schema as per the spec
3. The rust implementation of coserv spec (coserv-rs) contains the implementation of the discovery document

But I am fine with moving the issue to veraison/apiclient rather than here. Let me know what you think.

[thomas-fossati]

It feels slightly off, but I think I can live with that :-)

For reference, the server-side implementation can be found here: https://github.com/veraison/services/blob/main/coserv/api/discovery.go