[native] update Secondary Device Auth flow to support SIWE users

Summary:
ENG-6145.

ENG-9825

1. Turn functions into a hook
2. Update SecondaryDeviceQRCodeScanner to fetch credentials for both username/wallet users
3. Clean some code

Depends on D13846

Test Plan: Tested in D13849

Reviewers: varun, bartek

Reviewed By: varun, bartek

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D13847