[lib, web, native] Use KesyerverStore to get current cookie

Summary:
https://linear.app/comm/issue/ENG-4377/refactor-cookie-field-in-web-redux
Start using the cookie field from keyserverStore, in places where state.cookie was being fetched

In this first iteration we are hardcoding the id of our keyserver

Test Plan: ran yarn flow-all. Chekced with git grep that in all places the cookie from state was being used, the state.keyserverStore.keyserverInfos[].cookie is used instead (went through all occurences of 'cookie')

Reviewers: michal, kamil

Reviewed By: michal

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D8534