[web] Introduce user list modal

Summary:
This is a modal that can render both friend and block list.

Depends on D3674

Test Plan: Render the modal by providing functions and component and check if it looks ok.

Reviewers: benschac, atul, def-au1t, ashoat

Reviewed By: atul, ashoat

Subscribers: ashoat, Adrian, karol-bisztyga, yayabosh

Differential Revision: https://phabricator.ashoat.com/D3675