Add clearer saved search options in ApplicationSearch

Summary: Ref T5307, Makes these buttons a little more clear visually and verbosely. Adds white icons for blue buttons.

Test Plan: Test saving a search, viewing button changes on various form pages / uiexamples.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T5307

Differential Revision: https://secure.phabricator.com/D17305