[web] Introduce friend list modal row

Summary:
This component will be used on friend list to display a row containing username and buttons. https://www.figma.com/file/a1nkbWgbgjRlrOY9LVurTz/Comm-%2F-Desktop-app?node-id=1274%3A89558 The buttons will be added in next diffs. The avatars may be added later.

Depends on D3675

Test Plan: Display the component in a modal and check if it is rendered correctly.

Reviewers: benschac, atul, def-au1t

Reviewed By: benschac, atul

Subscribers: ashoat, Adrian, karol-bisztyga, yayabosh

Differential Revision: https://phabricator.ashoat.com/D3676