[lib] update device list when updating UserStore

Summary: ENG-7824.

Test Plan:

1. Add this code to master (with usingCommServicesAccessToken = true) and check if device lists are populated.
2. Make change in user store (e.g. add user) and verify is device list is fetched for this user.
3. Make sure this effect does not re-render when not needed.

Reviewers: tomek, bartek, inka

Reviewed By: tomek, inka

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D12330