Materials: Child ignoring parent material

Inherit the material from the parent object when creating a new object,
such as during a boolean operation, or when extruding a sketch.

fixes #15503

src/Mod/Part/App/FeatureMirroring.cpp

@@ -257,6 +257,8 @@ App::DocumentObjectExecReturn *Mirroring::execute()
         if (shape.isNull())
             Standard_Failure::Raise("Cannot mirror empty shape");
         this->Shape.setValue(TopoShape(0).makeElementMirror(shape,ax2));
+        copyMaterial(link);
+
         return Part::Feature::execute();
     }
     catch (Standard_Failure& e) {