changeName method
change name of account
Implementation
Future<KeyPairData> changeName(Keyring keyring, String name) async {
final json = keyring.current.toJson();
// update json meta data
service!.updateKeyPairMetaData(json, name);
// update keyPair date in storage
keyring.store.updateAccount(json);
return KeyPairData.fromJson(json);
}