Correctly scale the progress bar

[khdlr]

Minor fix (obscured by autoformatter stuff), really only changes:

    function loadingBarWrapperFunction(progress, total = 100) {
      return window.setSimulationProgress(progress)
    }

to

    function loadingBarWrapperFunction(progress, total) {
      return window.setSimulationProgress((progress * 100) / total)
    }

[khdlr]

This will work its full magic only together with open-pv/simshady#32 🪄 🔮