Send EVT_SLICING_UPDATE with RELOAD_SLA_SUPPORT_POINTS

once object's support points are calculated by the backend.

src/slic3r/GUI/Plater.cpp

@@ -2229,6 +2229,9 @@ void Plater::priv::on_slicing_update(SlicingStatusEvent &evt)
             break;
         }
     }
+    if (evt.status.flags & PrintBase::SlicingStatus::RELOAD_SLA_SUPPORT_POINTS) {
+        // Update SLA gizmo
+    }
 }
 
 void Plater::priv::on_slicing_completed(wxCommandEvent &)