add undo for control rig handles

Editor/SnappersHeadRendererEditor.cs

 						//		break;
 						//}
 
+						EditorGUI.BeginChangeCheck();
-
-						t.localPosition = pos;
-						t.localRotation = rot;
+						if (EditorGUI.EndChangeCheck())
+						{
+							Undo.RecordObject(t, "Move control rig handle");
+							t.localPosition = pos;
+							t.localRotation = rot;
+						}
 					}
 				}
 			}