R1:e81ec738f3ea

[Redesign] Add back limited header-color options

Summary: Ref T8099. Adds back basic header color options, which change the logo color instead. Also RAINBOW.

Test Plan:
tested each of the new colors.

{F442284}

Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T8099

Differential Revision: https://secure.phabricator.com/D13040