[Redesign] Better icon spacing for PHUIObjectListItem

Summary:
Ref T8099, Improve hit area for new icon, tweaks grippable spacing and app icon spacing.

Also Tablet layout updates

Test Plan: Test Maniphest home, Pinning apps, Dashboards

Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T8099

Differential Revision: https://secure.phabricator.com/D12986