R1:64dddc76c5cd

Remove Controller->getHandle() and Controller->loadHandles()

Summary: Ref T7689. Modernize all callsites of these methods.

Test Plan:
- Poked at dashboards.
- Pretty sure this code is technically unreachable right now.
- Viewed commit; viewed "Audit Status".
- Viewed a fund; viewed "Payable to"; viewed "Owner".
- Viewed herald rules; viewed "Author"; viewed "Applies To".
- Viewed a Legalpad document; viewed "Contributors".
- Viewed Phame post list; viewed blog; viewed post (viewed "Blog", viewed…