Aligning Tailwind and old EmotionCSS themes

[kmcginnes]

Description

• Uses colors defined in CSS variables for EmotionCSS styles
• Use Tailwind's stock neutral gray colors for the grays in the theme
• Tweak the grays for borders and backgrounds to soften them
• Tweak the background color of sidebar tab items
• Remove custom shadows from old theme to rely on stock Tailwind shadows
• Remove Card and use inline styles (each use was slightly unique anyway)
• Use Panel for Legend container for a consistent look
• Fix z-index issues with menus (select dropdown menus, context menu, etc)
• Update style of old Select menu to match context menu
• Update Panel style a tiny bit

Validation

Before	After

Related Issues

• Part of Use Tailwind & Radix #700

Check List

• I confirm that my contribution is made under the terms of the Apache 2.0
  license.
• I have run pnpm checks to ensure code compiles and meets standards.
• I have run pnpm test to check if all tests are passing.
• I have covered new added functionality with unit tests if necessary.
• I have added an entry in the Changelog.md.

[andreachild]

LGTM