use zbar + WASM as the fallback instead of jsqrcode

[monteslu]

jsqrcode has decent performance in the webworker, but its is much less accurate than zbar + WASM. Also zbar gives back the four corners of the qrcode's shape which makes it a better candidate for a proper polyfill to BarcodeDetector.

Did some proof of concept work here: https://github.com/monteslu/qr_perf

Live demo here: https://qrperf.netlify.com/

[PaulKinlan]

Ooooh, interesting. Nice.

I am thinking the following. Use this as fallback when shapedetection is not available, but WASM is, then use existing Worker model for devices that don't support either.

[PaulKinlan]

@paullewis who has been playing around with something similar (as FYI)