[web] Prepare a list of users that should be displayed

Summary:
Create a list of users and sort it by username.

Depends on D4269

Test Plan: Render the component and check if the list is sorted correctly.

Reviewers: def-au1t, atul

Reviewed By: atul

Subscribers: ashoat, Adrian, yayabosh

Differential Revision: https://phab.comm.dev/D4305