Grid class added to depict the planet
Remote set methods from the Position class as they are not used
Direction belongs to the Grid class, not the Rover

The Rover only knows what it’s current direction is
Fix compilation errors due to Direction class refactor
Direction enum moved from Rover to Grid
Methods to initialize the grid and place the rover on it
Overloading equals and hashCode methods for Position
Deleted RoverKata standalone class as it felt redundant
New GridHelper class to help plotting adjacent cells
Refactor Grid, Rover and Position classes
Fix logic bug in GridHelper for Y Axis coordinate
Update test cases to pass all