[lib] Create generic cookies selector

Summary:
https://linear.app/comm/issue/ENG-4377/refactor-cookie-field-in-web-redux
Creating a selector that will return a map of all cookies keyed by keyservers ids.

Test Plan: Checked that the selector returns the "map".

Reviewers: michal, kamil

Reviewed By: michal

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D8535