MultiDirectional Hill shade function does not return the correct out put

MultiDirectional Hill shade function add support for nodata handling

Start by locating the MultiDirectional Hill shade function and reproducing its behavior with raster inputs containing nodata values. Compare the current output with the expected nodata handling described by the project, then add or update focused coverage if the repository provides tests. Done means nodata cells are handled correctly without changing valid hillshade output.

Written by the indexing model from the issue text.