Rename Setpoint Schedule

The `SetpointSchedule` class ("smart_control/simulator/setpoint_schedule.py") isn't really about device setpoint ranges, but really represents the building's comfortable air temperature ranges.

We should consider renaming the class to more accurately reflect its purpose, perhaps `BuildingComfortSchedule` or `BuildingOperationalSchedule`.

This would allow us to add a new `SetpointSchedule` or `DeviceSetpointSchedule` class to handle the schedule of desired device setpoint values (air temperature, hot water heating temp, etc) in eco vs comfort mode.