R1:c8a279957dc1

Remove "DiffusionTagTableView"

Summary: Ref T13552. This older class has no callers; tag and branch listings were replaced with an "ObjectList" view.

Test Plan: Grepped for "DiffusionTagTableView", got no hits.

Maniphest Tasks: T13552

Differential Revision: https://secure.phabricator.com/D21407