Add other MLDSA test vectors

[DarkaMaul]

For testing certain codepaths for unsupported key sizes and key serialization, we need some extra vectors.

Extracted from #14404 per @alex's comment.

[reaperhulk]

mldsa44_priv.der appears to contain both seed and pub/priv so this is the OpenSSL "kitchen sink" format I think?

[facutuesca]

when I decode it I see this, which only contains the seed?

The OCTET STRING has tag 0, which should mean that it's the seed variant from the ML-DSA-44-PrivateKey CHOICE:

ML-DSA-44-PrivateKey ::= CHOICE {
  seed [0] OCTET STRING (SIZE (32)),
  expandedKey OCTET STRING (SIZE (2560)),
  both SEQUENCE {
      seed OCTET STRING (SIZE (32)),
      expandedKey OCTET STRING (SIZE (2560))
      }
  }

[reaperhulk]

This appears to have serialized nothing:

SEQUENCE {
  INTEGER { 0 }
  SEQUENCE {
    # ml-dsa-65
    OBJECT_IDENTIFIER { 2.16.840.1.101.3.4.3.18 }
  }
  OCTET_STRING {
    SEQUENCE {}
  }
}

[facutuesca]

I think that's intended, it's for a test for an invalid key:

def generate_mldsa65_noseed(output_dir: str) -> None:
    # ML-DSA-65 OID: 2.16.840.1.101.3.4.3.18
    # Generate an ML-DSA-65 PKCS#8 key whose inner privateKey is an
    # empty SEQUENCE (0x30 0x00) — i.e. the "both" SEQUENCE form with
    # no seed present. This exercises the InvalidKey error path in the
    # Rust parser when seed is None.

(from the script used to generate it)