Ref T6049, Add Phurl URL create capability

Summary: Ref T6049, Add Phurl URL create capability

Test Plan:

• Change Home → Applications → Phurl → Configure to allow no one to create Phurl URLs
• Attempt Phurl → Shorten URL. Should not be able to create a Phurl.

Reviewers: epriestley, Blessed Reviewers

Reviewed By: epriestley, Blessed Reviewers

Subscribers: Korvin

Maniphest Tasks: T6049

Differential Revision: https://secure.phabricator.com/D14510