Change disclosure icon color with prop

[alex-page]

WHY are these changes introduced?

Fixes #3925

WHAT is this pull request doing?

The icon color was set in SASS and incorrect on the icon. This removes the SASS and provides the color through the Icon component.

How to 🎩

🖥 Local development instructions
🗒 General tophatting guidelines
📄 Changelog guidelines

Copy-paste this code in playground/Playground.tsx:

import React from 'react';
import {Page} from '../src';

export function Playground() {
  return (
    <Page title="Playground">
      {/* Add the code you want to test in here */}
    </Page>
  );
}

🎩 checklist

• Tested on mobile
• Tested on multiple browsers
• Tested for accessibility
• Updated the component's README.md with documentation changes
• Tophatted documentation changes in the style guide
• For visual design changes, pinged one of @ HYPD, @ mirualves, @ sarahill, or @ ry5n to update the Polaris UI kit

[github-actions]

🟢 This pull request modifies 3 files and might impact 1 other files.

Details:

All files potentially affected (total: 1)

• /src/components/Tabs/Tabs.tsx

📄 UNRELEASED.md (total: 0)

Files potentially affected (total: 0)

🎨 src/components/Tabs/Tabs.scss (total: 1)

Files potentially affected (total: 1)

• /src/components/Tabs/Tabs.tsx

🧩 src/components/Tabs/Tabs.tsx (total: 0)

Files potentially affected (total: 0)