Freeze Spawn State For Auto Create Units

when switching between dojo Yumi and Ashigaru, dog soldiers and fertility ceremony, or wood and cannon in the factory, their spawn timer should freeze and be remembered rather than completely reset.

this would help average skilled players and the ai the most, and allow for more player freedom and micro by allowing players to switch to resources when they need to without falling into a sunk cost fallacy, one that is very punishing and feels bad.