[web] add icons, reply and chevron small

Summary: screenshot, add these two

Test Plan: n/a make sure icons in the app don't break

Reviewers: atul, ashoat

Reviewed By: ashoat

Subscribers: ashoat, palys-swm, Adrian, karol-bisztyga

Differential Revision: https://phabricator.ashoat.com/D3167