Provide result type information in tokenizers

Summary:
Ref T1279. The new dual-mode user/project tokenizers are a bit disorienting. Provide content type hints.

Very open to any suggestions here, most of this patch is just getting the right data in the right places. We can change things up pretty easily.

• I like the little icons in the tokens themselves, I think they look good and are useful.
• I'm less sold on the '(Project)' thing I did in the dropdown. We can easily make this richer if you have thoughts on it -- we could put icons in the left column maybe? Or right-justify the types?
• I made it always sort users above projects.

Test Plan: See screenshot.

Reviewers: chad, btrahan

Reviewed By: btrahan

CC: chad, aran, carl

Maniphest Tasks: T4420, T1279

Differential Revision: https://secure.phabricator.com/D7250