Fix T85947: Missing check of master collection for objects being instanced.

`object_in_any_collection` used during linking/appending to check
whether an object is already instanced by at least one collection, was
not taking into account embedded master collections from scenes.

source/blender/blenloader/intern/readfile.c

@@ -4600,6 +4600,13 @@ static bool object_in_any_collection(Main *bmain, Object *ob)
     }
   }
 
+  LISTBASE_FOREACH (Scene *, scene, &bmain->scenes) {
+    if (scene->master_collection != NULL &&
+        BKE_collection_has_object(scene->master_collection, ob)) {
+      return true;
+    }
+  }
+
   return false;
 }