Provide hovercards for generic edge stories, and include more message information in commit hovercards
Summary:
Ref T13620.
- Make generic edge stories render links with hovercards. Other story types (like subscriptions) already do this so I'm fairly certain this is just old code from before hovercards.
- Include a longer commit message snippet in hovercards.
Test Plan: {F8465645}
Maniphest Tasks: T13620
Differential Revision: https://secure.phabricator.com/D21574