feat(srp): add render layer filtering to scene draw

- carry MeshRenderer renderLayer through scene extraction into VisibleRenderItem
- extend native and managed FilteringSettings with renderLayerMask support
- let RenderObjectsRendererFeature author layer-filtered object draws

managed/XCEngine.ScriptCore/Rendering/Core/FilteringSettings.cs

@@ -7,6 +7,7 @@ namespace XCEngine.Rendering
     {
         public int renderQueueMin;
         public int renderQueueMax;
+        public uint renderLayerMask;
 
         [MarshalAs(UnmanagedType.I1)]
         public bool requireShadowCasting;
@@ -34,7 +35,8 @@ namespace XCEngine.Rendering
         {
             return new FilteringSettings
             {
-                renderQueueRange = renderQueueRange
+                renderQueueRange = renderQueueRange,
+                renderLayerMask = uint.MaxValue
             };
         }