Standardize prepare time for ranged units.
Prepare time is the time between an attack order and the arrows actually flying.
Archers go from 500ms to 800ms standard, making them slower to fire than other ranged units, and making them slightly harder to micro against e.g. raids.
Javelineers go from 750ms to 400ms, for the opposite effect.
Crossbowmen, as a 'special' feature, get 200ms, meaning they fire their first volley really fast despite their long repeat rate.
This also standardizes all javelineer units to have 1250ms repeat time.
Differential Revision: https://code.wildfiregames.com/D4050