Add option for export of waveform with transparent background

[pietrop]

Is your feature request related to a problem? Please describe.

Describe the solution you'd like

Add option for export of waveform with transparent background doc https://autoedit.gitbook.io/autoedit-3-user-manual/7.-export/export-animated-waveform

code https://github.com/pietrop/digital-paper-edit-electron/blob/master/src/ElectronWrapper/ffmpeg-remix/index.js#L48

Describe alternatives you've considered

NA

Additional context

ffmpeg -i test.mp4 -filter_complex "showwaves=s=1920x1080:colors=white:mode=cline" -c:v prores_ks -pix_fmt yuva444p10le transparent.mov