[SimulationEngine][Feed][Animal] Disentangle Feed degradations from Animal ration planning

[ew3361zh]

Note: This issue should wait until #2735 is closed/completed (it feels close to complete at the writing of this issue).

in SimulationEngine, ration planning (in HerdManager) is tied up with feed degradations (in FeedManager). It is desirable to be able to run these modules (Feed and Animal) independently so that they're not dependent on one another.

I think this will require some SME input because if there are no feed degradations occurring when animals are simulated, ration planning still needs to occur somehow - maybe there is a SME-determined default amount of feed available at every ration planning interval in that case?

Functions to look at in SimulationEngine:

• _execute_daily_animal_operations()
• _formulate_ration()
• _execute_feed_planning()

Note: if these above functions are not in SimulationEngine, look through the self.feed_manager calls throughout the class and make sure they're independent of allself.herd_manager calls.