Investigate adding CoRIM support for future TDX attestation

This is a WIP stub issue - to be expanded soon.

[CoRIM](https://datatracker.ietf.org/doc/draft-ietf-rats-corim/) appears to be gaining adoption and will be used by the upcoming version of TDX. [Intel CoRIM Profile](https://datatracker.ietf.org/doc/draft-cds-rats-intel-corim-profile/)

In my understanding this would replace the collateral format provided by Intel PCS.

Investigate what Rust tooling exists for hadling CoRIM, and what it would take to support these.

The most actively maintained crate i have found is Azure's `corim`: https://docs.rs/corim/

Start with the CoRIM draft, the Intel CoRIM Profile, and Azure's Rust `corim` crate linked in the issue. Inspect the repository's existing attestation and collateral support to determine what integration points are affected. Done means documenting the available Rust tooling and the work required to support CoRIM for future TDX attestation.

Written by the indexing model from the issue text.