[lib][native] Add logOutPrimaryDevice to Identity Client

Summary:
Added logOutPrimaryDevice function to identity client context.
Similarly to e.g. registerPasswordUser, it creates singleton device list on its own.

Renamed createInitialDeviceList to createSingletonDeviceList - this name is more universal.
It can be also re-used during backup restore.

Depends on D12585

Test Plan:
Tested against local identity. Confirmed that when identityClient.logOutPrimaryDevice() is called,
identity service receives valid device list payload.

Reviewers: kamil, varun

Reviewed By: kamil

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D12586