extend the "get spectra viewer as Blob" functionality

@lpatiny

Inside the nmrXiv that is needed to export not only the spectra that are displayed in the Display but they need advanced options to get spectra one by one in SVG format in one command instead of hiding and showing spectra or switching between the nucleus tab in the spectra panel manually.

Why do they need that? because they display images or previews of the images of each spectrum as a slider to show what are the spectra inside the "project" or "sample".