[pack] ensuring that we look at the same InStandbyMode value during app initialization #4356
@fabiocav / @mathewc -- take a look at my latest change. It addresses Mathew's concern but at the sake of more complicated wire-up. In order to get things firing in the correct order, I needed to make sure the StandbyOptions cache was invalidated first and then the ScriptApplicationHostOptions can react to that by invalidating its own.
I kept this a separate commit so I can roll it back if we decide it's not worth it...