Utilize `PhutilMethodNotImplementedException`

Summary: Depends on D9992. Utilize the `PhutilMethodNotImplementedException` class.

Test Plan: N/A

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D10000