[Redesign] Spaces header colors

Summary: Ref T8099, Gives some additional prominence to a Space (darkred) in headers and obj lists.

Test Plan: Test a sample space. Some concern on workboards if space name is long.

Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: epriestley, Korvin

Maniphest Tasks: T8099

Differential Revision: https://secure.phabricator.com/D13312