Scene Picker: Modified scene groups to contain LoadAsGroup, SortAsGroup and SortInSubmenuAsGroup

### Changed
-  Scene groups to contain three different types of behaviours for grouping:
   - Load As Group: Groups all scenes into a single entry
   - Sort As Group: Sorts all scenes into entries close to each other in the dropdown
   - Sort In Submenu As Group: Sorts all scenes into entries in a submenu

### Removed
- Removed "Scene sorting by Asset label" groups

Editor/Toolbar/Tools/ScenePickerObjects/SceneGroup.cs

@@ -8,7 +8,9 @@ namespace Module.NavigationTool.Editor.Toolbar
     {
         public string name;
         public ESceneGroupFilterType filterType;
+        public ESceneGroupBehaviourType behaviourType;
         public string optionalMainScenePath;
+        public string subMenuPath = "Submenu";
         public List<string> filters = new();
     }
 }