feat: add nvidia GPU evidence format spec

[thomas-fossati]

Based on discussion with @jraman567

[thomas-fossati]

Once this is merged, the request to IANA can be kicked off.

The entry point for the registration is https://www.iana.org/form/media-types

The information to supply is the following:

---

Name: Jag Raman

Email: jag.raman@oracle.com

Media type name: application

Media subtype name: vnd.veraison.nvidia-gpu-evidence+json

Required parameters: N/A.

Optional parameters: N/A.

Encoding considerations: binary

JSON is UTF-8-encoded text

Security considerations: The requested media type does not contain active or executable content.

The information contained in the media type requires privacy and integrity services to be applied to the transport mechanism.
When using the media type in REST APIs over HTTPS or CoAPS, the necessary security services are provided by TLS or OSCORE, respectively.
For all other use cases, users of this media type must ensure that the correct secure transport mechanism is utilised.

The security considerations in Section 12 of RFC 8259 apply fully.

Please note that this media type does not employ compression or incorporate links that must be referenced in order to interpret the type correctly.

Interoperability considerations: N/A.

Published specification: https://github.com/veraison/ratsd/blob/main/docs/nvidia-gpu-evidence.cddl

Applications which use this media: This media type is exchanged by Attesters and Verifiers (RFC9334), typically in REST APIs over HTTPS or CoAPS.

Fragment identifier considerations: The syntax and semantics of fragment identifiers are as specified for "application/json". (No fragment identification syntax is currently defined for "application/json".)

Restrictions on usage: none

Provisional registration? (standards tree only): No

Additional information:

1. Deprecated alias names for this type: N/A.
2. Magic number(s): N/A.
3. File extension(s): N/A.
4. Macintosh file type code: N/A.
5. Object Identifiers: N/A.

General Comments:

Person to contact for further information:

1. Name: Jag Raman
2. Email: jag.raman@oracle.com

Intended usage: COMMON

Author/Change controller: Veraison project (veraison@lists.confidentialcomputing.io)

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[cowbon]

Should arch-type be a generic string to support future GPU arch in CDDL?