Support WebUSB

[XanderLeaDaren]

As far as I know, only Chrom(ium)-based browsers provide WebUSB nowadays.

It would be great to help migration from these browser that Zen implements this API, where Mozilla decided till now not to do it — by the way, it would help migrate some people from Firefox to Zen as well.

For (personal) context: currently, I and other collegues teachers have a NumWorks calculator, and updates & Python script transfer are handled by WebUSB; we’re stuck on having another browser aside just for this, and I’m pretty sure other people rely on WebUSB for other devices.

As a reference, a link to discussion about this topic on Mozilla Connect:
https://connect.mozilla.org/t5/ideas/fully-support-web-usb-and-web-serial/idi-p/62