Replace o-brand with a design token implementation

[notlee]

Replace o-brand with a design token implementation. We haven't figured out exactly how a design token implementation should look. We have an example with o-buttons in the design token exploration draft PR. Sass generated with design tokens, to replace o-brand, should remain private for now.

• [ ] o-share
• [ ] o-overlay
• [ ] o-message
• [ ] o-layout
• [ ] o-loading
• [ ] o-labels
• [ ] o-table
• [ ] o-header-services
• [ ] o-header
• [ ] o-fonts
• [ ] o-forms
• [ ] o-editorial-layout
• [ ] o-buttons
• [ ] o-autocomplete
• [ ] o-footer-services
• [ ] o-footer
• [ ] o-colors
• [ ] o-tabs

Relates to: Design token proposal.