Use text ellipsis on hovercard tags

Summary: Fixes T12326. Users can make really log tag titles, this forces ellipsis if it is too long.

Test Plan: Write a super long tag, see ellipisis. Test a small tag, see normal layout.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T12326

Differential Revision: https://secure.phabricator.com/D17486