feat: re-implement (native) Gizmo class, expose preserveScaling parameter for setParent, add methods for getting viewport bounding box from renderable entity

thermion_dart/lib/thermion_dart/entities/abstract_gizmo.dart

@@ -1,3 +1,23 @@
 
 
 
+import 'package:thermion_dart/thermion_dart/thermion_viewer.dart';
+import 'package:vector_math/vector_math_64.dart';
+
+abstract class AbstractGizmo {
+  bool get isActive;
+
+  void translate(double transX, double transY);
+
+  void reset();
+
+  void attach(ThermionEntity entity);
+
+  void detach();
+
+  Aabb2 boundingBox = Aabb2();
+
+  void checkHover(double x, double y) { 
+    if(boundingBox.containsVector2(Vector2(x, y)));
+  }
+}