[lib, web] Use sessionId from keyserverStore

Summary:
issue: https://linear.app/comm/issue/ENG-4457/refactor-sessionid-field
Start reducing sessionID in keyserverStore and using it in places where we were using sessionID redux field.

Test Plan:
Ran yarn flow-all. Checked that sessionID field in keyserverStore has the same value as sessionID redux field when user loges out,
logs in.

Reviewers: michal, kamil

Reviewed By: michal

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D8645