…al Drain Direction (LDD) raster file

This commit refactors the logic for creating the Local Drain Direction (LDD) map in the RUBEM class. Instead of always generating the LDD map based on the DEM, the code now checks if a specific LDD file is provided. If a file is provided, it reads the LDD map from the file. If no file is provided, it generates the LDD map based on the DEM.

…fy-local-drain-direction-ldd-raster-in-the-model-configuration