Fix #104982: Ensure view layer when baking line art.

This is more like a hack, which ensures view layer depsgraph evaluation
when baking line art. It should fix the problem where the camera marker
switch would cause `view_layer->object_bases_array == null`.

Pull Request: https://projects.blender.org/blender/blender/pulls/117227

source/blender/gpencil_modifiers_legacy/intern/lineart/lineart_ops.cc

@@ -237,6 +237,7 @@ static void lineart_gpencil_bake_startjob(void *customdata, wmJobWorkerStatus *w
 
     BKE_scene_frame_set(bj->scene, frame);
     BKE_scene_graph_update_for_newframe(bj->dg);
+    DEG_graph_build_from_view_layer(bj->dg);
 
     for (LinkNode *l = bj->objects; l; l = l->next) {
       Object *ob = static_cast<Object *>(l->link);