[native] Handle invalid CSAT in Identity RPCs

Summary:
Part of ENG-6664

Depends on D13992

Test Plan: Manual testing with mocked invalid access token. Identity authed RPC calls end up with logout.

Reviewers: kamil, varun

Reviewed By: kamil

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D14024