[web] Use SWM Icons in Menu component

Summary:
Replace FontAwesome icons with correct ones from SWM Icon Pack (following Figma design)

Test Plan: Run web app and check if icons are correct in thread actions menu and members actions menu in members modal.

Reviewers: palys-swm, benschac, atul

Reviewed By: palys-swm

Subscribers: ashoat, Adrian, atul, karol-bisztyga, benschac

Differential Revision: https://phabricator.ashoat.com/D3479