Add some new Dashboard icons

Summary: Ref T10390. Fixes the missing "fa-dashboard" icon and adds a few more for an even 25.

Test Plan: Create new dashboard, see dashboard icon, select new dashboard icon.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T10390

Differential Revision: https://secure.phabricator.com/D17526