[web] fix input icons to be the correct size

Summary:
re-size the icons with padding,

before:

after:

Test Plan: check figma, make sure the icons are the correct size: https://www.figma.com/file/a1nkbWgbgjRlrOY9LVurTz/Comm-%2F-Desktop-app?node-id=1170%3A79456

Reviewers: atul

Reviewed By: atul

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

Differential Revision: https://phabricator.ashoat.com/D3300