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

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