[lib] rename QRAuthContext to SecondaryDeviceQRAuthContext

Summary: In D14105 I introduced context and turned out, that what I added and existing context on the secondary side have the same names, to avoid confusion I am renaming them to SecondaryDeviceQRAuthContext and PrimaryDeviceQRAuthContext.

Test Plan: Flow

Reviewers: bartek, tomek

Reviewed By: bartek

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D14166