Allow adding multiple xPubs from QR signers

[ben-kaufman]

Some QR signers like Jade and SeedSigner only export a single type of xpub with each QR. We should allow the user to scan multiple and show the progress on each one that is scanned. Normally it'll just be the single sig and multi sig xpubs, but there could be extra like the taproot xpub. It shouldn't be mandatory to export all to add the device, but we should allow adding multiple at the same time, and potentially allow to add more from the device settings.