Consistently refer to 'Projects' as 'Tags'

Summary:
In calendar, dashboard, diffusion, diviner, feed, fund,
maniphest, pholio, ponder, and slowvote use the term 'tags' if possible.

This intenctionally skips diffusion, differential, and the projects application itself.

Ref T10326 Ref T10349

Test Plan: inspection on a running, locally modified, system

Reviewers: avivey, epriestley, Blessed Reviewers

Reviewed By: epriestley, Blessed Reviewers

Subscribers: Korvin

Maniphest Tasks: T10835, T10326, T10349

Differential Revision: https://secure.phabricator.com/D15753