Validate a quantity on its own. Split out from validateOrder because a
market order has no price, and the freeze and lot limits must still apply to
it: routing quantity checks through the price path left them unreachable for
exactly the orders that are hardest to take back.
Validate a quantity on its own. Split out from
validateOrderbecause a market order has no price, and the freeze and lot limits must still apply to it: routing quantity checks through the price path left them unreachable for exactly the orders that are hardest to take back.