@description Takes a single raster that is a factor and creates
a new SpatRaster that contains the individual levels.
@param ras A SpatRaster object that is a factor. Alternatively a SpatRaster object
can be supplied in which only factor variables are 'exploded'.
@param name An optional character name for the SpatRaster.
@param ... Other parameters (not used).
@returns A SpatRaster object.
@keywords utils, internal
@noRd