Remove the "Phragment" application

Summary:
Ref T5479. Ref T13658. This was a contributed application from the early days of Phabricator which never had customers or users in the wild. The contributor moved on from the project many years ago.

Any capabilities in this general role would look different today. It also has one or two product name literal strings, so this is as good a time as any to remove it.

This change does not remove storage; I'll issue upgrade guidance and do that separately after some time.

Test Plan: Grepped for "phragment", got no relevant hits.

Subscribers: hach-que, PHID-OPKG-gm6ozazyms6q6i22gyam

Maniphest Tasks: T13658, T5479

Differential Revision: https://secure.phabricator.com/D21793