[Redesign] PHUICrumbs touchups

Summary: Ref T8099, minor adds back the border, makes blue highlight {$blue}

Test Plan: Hover over new crumbs, match header hovers. Check Phriction for border

Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T8099

Differential Revision: https://secure.phabricator.com/D12959