fix(ImageMapper): NEAREST instead of NEAREST_MIPMAP_NEAREST
fix(ImageMapper): NEAREST instead of NEAREST_MIPMAP_NEAREST

With the Nearest InterpolationType, we intend to display the original
data, so use NEAREST instead of NEAREST_MIPMAP_NEAREST, which may
provide an interpolated value.

Suggested-by: Ken Martin <62024bbe3208243fb770aa74834abd3fed0f9a60@kitware.com>

Kitware/vtk-js,Kitware/vtk-js,Kitware/vtk-js,Kitware/vtk-js