Update Eurydice for combined header-only C extraction of ML-KEM & ML-DSA #1328

Would it be possible to make a c_header_only extract for ML-DSA, similar to the existing one for ML-KEM.

AFAIK the existing libcrux-ml-dsa/cg extract targets C++, but I'd like to use libcrux' ML-DSA support in OpenSSH, which is a vanilla C project.