Horizon LOS in water should be typically around 5km, so extend the
dimentions of the water to allow 5km in any direction.
With regard to the wave shader, we extend the original MeshInstance to
2000x2000 using a reasonable tradeoff of virtex subdivisions. The
remainder of the area is covered by another water plane, subdivided to a
much lower level of detail. The area at the center of the large 'outer'
water plane is subtracted so that the two do not overlap.
Co-authored-by: dusoleil <howcansocksbereal@gmail.com>