[web] Rename deviceKeys to qrData in QRCodeLogin

Summary:
This makes it more consistent with QRCodeScreen on native.

Depends on D12109

Test Plan: I tested the flow using staging, with my phone as a primary device and a local simulator as a secondary device

Reviewers: bartek

Reviewed By: bartek

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D12110