Wrap really long text properly in diffs

Summary: Fixes T11236, breaks long words and inlines the spans.

Test Plan:
Use a diff with super long text like SSH keys, set Font to 24/48 Impact

{F1705910}

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T11236

Differential Revision: https://secure.phabricator.com/D16198