Function hpke_kdf::LabeledExpand

pub fn LabeledExpand(
    alg: KDF, 
    suite_id: &ByteSeq, 
    prk: &ByteSeq, 
    label: &ByteSeq, 
    info: &Info, 
    L: usize
) -> HpkeByteSeqResult

KDF: Labeled Expand

def LabeledExpand(prk, label, info, L):
  labeled_info = concat(I2OSP(L, 2), "HPKE-v1", suite_id,
                        label, info)
  return Expand(prk, labeled_info, L)