chore: add @gitlab/ui and tailwind

Purpose

!1120 (merged) proposes adding illustration design tokens to gitlab-svgs SVG files. gitlab-svgs current doesn't include GitLab UI styles, most importantly @gitlab/ui/src/scss/gitlab_ui to include design token CSS custom properties automatically.

This MR proposes using @gitlab/ui for interface components and removing custom styles so that gitlab-svgs resembles a more accruate consumption of icons and design tokens.

Screenshots

Checklist

For a new icon and/or illustration:

• Link to related design issue:
• If this adds an icon ensure that it follows the new icon checklists.
• If this adds an illustration ensure that it follows the new illustration checklists.

For third-party trademarks:

• If this adds or updates an icon or illustration that includes a third-party trademark, ensure that it follows the process for adding third-party trademarks to GitLab.