[processing][grass] Correctly return the actual generated filename

locations as the algorithm results, don't just echo back the parameter
value

Otherwise we don't return the correct value for temporary file locations
or for file paths during model execution

Fixes #36379

python/plugins/processing/algs/grass7/Grass7Algorithm.py

@@ -772,6 +772,8 @@ def exportRasterLayerFromParameter(self, name, parameters, context, colorTable=T
         metaOpt = self.parameterAsString(parameters, self.GRASS_RASTER_FORMAT_META, context)
         self.exportRasterLayer(grassName, fileName, colorTable, outFormat, createOpt, metaOpt)
 
+        self.fileOutputs[name] = fileName
+
     def exportRasterLayer(self, grassName, fileName,
                           colorTable=True, outFormat='GTiff',
                           createOpt=None,
@@ -947,6 +949,8 @@ def exportVectorLayerFromParameter(self, name, parameters, context, layer=None,
         exportnocat = self.parameterAsBoolean(parameters, self.GRASS_VECTOR_EXPORT_NOCAT, context)
         self.exportVectorLayer(grassName, fileName, layer, nocats, dataType, outFormat, dsco, lco, exportnocat)
 
+        self.fileOutputs[name] = fileName
+
     def exportVectorLayer(self, grassName, fileName, layer=None, nocats=False, dataType='auto',
                           outFormat=None, dsco=None, lco=None, exportnocat=False):
         """