Add addLinkSection to MailBody to properly format URIs

Summary: Fixes T6343. Grepped for all callsites and added addLinkSection where needed.

Test Plan: Tested Differential, Maniphest, Conpherence, Ponder and Macro. Inspect HTML mail for anchor tags. Inspect text mails for non-disruption.

Reviewers: epriestley, btrahan

Reviewed By: btrahan

Subscribers: talshiri, Korvin, epriestley

Maniphest Tasks: T6343

Differential Revision: https://secure.phabricator.com/D10762