Make token UI stronger and more consistent

Summary:
Ref T4100. Overall:

• Use token background color to communicate token type (blue = object, yellow = function, grey = disabled/closed, red = invalid).
• Use token icon color to make color choices consistent (specifically, use project icon colors in project tokens).
• For functions, use token icon to communicate function result type (e.g., viewer() has a user icon; members(...) has a group icon), since we don't need the icon to indicate "this is a function" anymore.

Test Plan:

Reviewers: chad, btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T4100

Differential Revision: https://secure.phabricator.com/D12446