Update Config app for handleRequest

Summary: Update all found callsites in Config.

Test Plan: Check setup issues, databases, edit a value, remove a warning, everything I could click on.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: epriestley, Korvin

Maniphest Tasks: T8628

Differential Revision: https://secure.phabricator.com/D13727