Fix camera orientation widget positioning

- invoke WindowResizeEvent when size changes.
- vtk/vtk!10622 removed the call to Superclass:SetSize which invoked WindowResizeEvent. This commit brings back the equivalent code.

Rendering/OpenGL2/vtkSDL2OpenGLRenderWindow.cxx

@@ -162,6 +162,8 @@ void vtkSDL2OpenGLRenderWindow::SetSize(int x, int y)
     {
       this->Interactor->SetSize(this->Size[0], this->Size[1]);
     }
+    this->Modified();
+    this->InvokeEvent(vtkCommand::WindowResizeEvent, nullptr);
   }
 }