Remember to add weapon per-shot resource costs to `Spring.SetUnitWeaponState`

Bill of materials to be done before starting this ticket:
* #940

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In theory adding "metalPerShot" (and energy) could be done already if somebody really insists, but this is going to make it annoying to design a general interface with arbitrary resources. I don't think gluing strings (`resourceName .. "PerShot"`) to make a key would be nice.