Update protocol tokens and assets

[maureenlholland]

Description

Updates assets to add icon viewboxes & updates Mozilla brand colors (I didn't see any instances of the old variables in use when searching the codebase, so assume they were only applied in consumer projects, if at all)

• I have documented this change in the design system.
• I have recorded this change in CHANGELOG.md.

Issue

#1074

Testing

• http://localhost:3000/docs/fundamentals/color

[maureenlholland]

re: assets

• the big change was already reviewed in Update protocol assets #1073
• this patch update is to fix missing viewBox attributes

re: tokens

• breaking change! will need protocol-specific changes before ready to review

[stephaniehobson]

Oh I already had a local branch going for the tokens 🤦‍♀️ Grab anything you like from it: main...tokens

[maureenlholland]

Moved up & added brand titles, but kept most of the color-specific sectioning in order to have a column-like overview of the +1, -1, -2 variants

[stephaniehobson]

R+ 🌈