R1:bb9b25a7ba79

Remove the `PhortuneNotImplementedException` class

Summary: Replace `PhortuneNotImplementedException` with `PhutilMethodNotImplementedException`.

Test Plan: N/A

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D14445