[FR] Alternate overhang perimeters extruding directions

[vovodroid]

There is such option in Orca/SuperSlicer, and it definitely helps:

I've implemented it in GCodeGenerator::extrude_entity

        if (this->config().overhangs_reverse) {
            for (ExtrusionPath el: loop->paths)
                if (el.role().is_overhang_perimeter() && this->m_layer->id() % 2 == 1) { 
                    reverse = true;
                    break;
                }
        }
        return this->extrude_loop(*loop, reverse, smooth_path_cache, description, speed);

So if it looks acceptable I can create PR, or rewrite it in more suitable way.