A general tidy-up for vehicle code to make things easier in the future. - Split BaseVehicle into BaseVehicle, BaseVehicle.Server, and BaseVehicle.Client. - Move IsWaterlogged and CanRunEngine checks to VehicleEngineController, so they can be shared by everything with an engine. - Match EntityFuelSystem and VehicleEngineController to Rust code formatting ('private' written out, spaces inside brackets). - BaseVehicle IsMounted implementation fix.