[protos] Add RPC for secondary device logout

Summary:
Addresses ENG-7886.
Introduced LogOutSecondaryDevice RPC which is going to be called by secondary device when user clicks the logout button.
This is part of the "CSAT invalidation flow" described in ENG-5293.

In contrast to the existing LogOutUser RPC, this one will only clear CSAT and device keys, but won't be modifying the device list.

Depends on D12091

Test Plan: CI. Implementation later in the stack

Reviewers: ashoat, varun, kamil, will

Reviewed By: kamil

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D12119