[Redesign] Update Workboards

Summary: Ref T8099, Cleans up Workboard UI, fixes button icon spacing

Test Plan: Review workboards on desktop, mobile

Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: epriestley, Korvin

Maniphest Tasks: T8099

Differential Revision: https://secure.phabricator.com/D13473