signToCompact function
Implementation
String signToCompact(
{required Uint8List message, required Uint8List privateKey}) {
final sig = EcdaSignature.signForEth(message, privateKey);
final recoveryParam = 1 - sig.v % 2;
final s = sig.s;
if (recoveryParam > 0) s[0] |= 0x80;
return concatSigCompact((sig.r), s);
}