BUG: allow DisableMouseInteraction in LaparoscopicCamera

In the LaparoscopicCamera example the mouse interaction
was supposed to be disabled, but by setting the new
interactor style after the viewer initialization, the
observers rules on the vtkViewer interactor were
overridden. Placing the interactorStyle beforehand
resolves the issue.

In the future it would be convenient to have wrapped
functions in IMSTK to make changes to the interactor
without the need to go through VTK.