[web] Introduce CommIcon component

Summary:
Use the same lib/shared/comm-icon-config.json (exported from IcoMoon) as we're using for CommIcon on native. This ensures that CommIcon on native and web are synced up. Before the icons from IcoMoon were exported separately on native and web which led to some inconsistency.

Heavily inspired by the SWMansionIcon.react.js component in the same directory.

Test Plan: Was able to consume CommIcon component as expected. Tested implicitly by subsequent diffs that replace some usages of SWMansionIcon with CommIcon.

Reviewers: abosh, varun, tomek, jacek

Reviewed By: abosh, varun

Subscribers: ashoat, adrian

Differential Revision: https://phab.comm.dev/D4850