Make ObjectItem default as "Card"

Summary: This went smoother than expeced. Makes the rounded Card the default, also tweaked selected state a little.

Test Plan:
Test UIExamples, Maniphest, Home, Differential, Harbormaster, Audit. Everything seems normal

{F163971}

{F163973}

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9408