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/ToolBuild.cs

@@ -1,7 +1,6 @@
 using JetBrains.Annotations;
 using UnityEditor;
 using UnityEngine;
-using UTools = UnityEditor.Tools;
 
 namespace Module.NavigationTool.Editor.Toolbar
 {