Function resolve_oci_config 

pub(crate) fn resolve_oci_config<ObjectID: FsVerityHashValue>(
    repo: &Repository<ObjectID>,
    reference: &OciReference,
    verity_override: Option<ObjectID>,
) -> Result<(OciDigest, Option<ObjectID>)>

Resolve an OciReference to a config digest and optional verity.

When resolving via a named ref, the verity override is ignored since the image metadata provides the correct verity.