[lib] Add device list signatures to Flow types

Summary:
Added client-side fields for device list signatures, according to Whitepaper 6.2.3

Depends on D11777

Test Plan: Flow, existing device list logic stays unchanged (QR auth still works)

Reviewers: kamil, varun

Reviewed By: kamil

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D11778