Allow user to specify n turbines and layout specs instead of a full x/y to start with #125
Description
Currently we force users to include an initial plant design in the windIO file, but it would be good to allow for specifying just grid parameters or parameters of some other layout or even just a target number of turbines or just to determine the turbines and locations based on optimization (e.g. with DEBO). To accomplish this we may need to have a catch prior to windIO validation that instantiates turbine initial locations.