The wellModel is now persistent over the time steps,
with an update method called every reportStep/episode.
This allows the following simplifications:
1. move the wellState to the WellModel
2. add a ref to the ebosSimulator to the wellModel
3. clean up the parameters passed to the wellModel methods
4. move RESV handling to the WellModel and the rateConverter
5. move the econLimit update to the WellModel