[lib] Allow keyserverAuth to update currentAsOf

Summary:
Noticed that I was getting FULL_STATE_SYNC after a successful session recovery. It was because the client wasn't updating currentAsOf on keyserverAuth, and then when the socket connected it would go into this condition.

Depends on D11503

Test Plan: Confirm that we get an INCREMENTAL_STATE_SYNC instead of a FULL_STATE_SYNC via web client, and confirm via console.log that the above codepath was not activated on keyserver

Reviewers: tomek, inka

Reviewed By: tomek

Differential Revision: https://phab.comm.dev/D11504