[Redesign] Update Feed

Summary: Ref T8099, minor spacing improvements and more icons for feed.

Test Plan:
Test feed in Feed, in a Dashboard, Profile, and Project

Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T8099

Differential Revision: https://secure.phabricator.com/D13045