[color] Add the material omnibox color mixer

This CL adds the material_omnibox_color_mixer to the pipeline
behind the kChromeRefresh2023 feature flag.

The material omnibox color mixer is intended to override colors
defined in the existing chrome color mixer when applied.

The current omnibox color mixer defines many leaf node color
relationships in terms of reasonable input colors. E.g.

  mixer[kColorOmniboxSecurityChipDangerous] =
    security_chip_color(gfx::kGoogleRed300, gfx::kGoogleRed600);

The intention is to preserve and continue to leverage these
relationships, only overriding colors as needed by the new
GM3 spec.

Following a complete rollout these GM3 overrides can be merged
back into the original chrome color mixer.

This CL also performs some small cleanups to existing mixers
(eliminating whitespace, comment formatting etc).

Bug: 1408542
Change-Id: Ibf0d5921e252d1d8b1a50b4f667859871d5e5327
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4356938
Commit-Queue: Thomas Lukaszewicz <tluk@chromium.org>
Reviewed-by: Allen Bauer <kylixrd@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1119978}