Add a DiffusionTagListView

Summary: Moves DiffusionTagsListView to uhhh, list. Separates out table view which is still in use now, implements mobile friendly UI for tags.

Test Plan:
Review KDE's Krita repository locally with lots of tags, desktop and mobile.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T12824

Differential Revision: https://secure.phabricator.com/D18115