* LiquidAccounts use the require_vaccount macro in place of the require_auth macro for authenticating a LiquidAccount against the key assigned when calling regaccount
* @param {name} - vaccount from payload
* require_vaccount(payload.vaccount);
void required_key(const eosio::public_key& pubkey){ \
eosio::check(_pubkey == pubkey, "wrong public key"); \
void require_vaccount(name vaccount){ \
auto pkey = handleNonce(vaccount); \