[Color System] Apply CS to Indicator component

[dleroux]

WHY are these changes introduced?

addresses: https://github.com/Shopify/polaris-ux/issues/349

WHAT is this pull request doing?

Paired with Miru apply CS to Indicator component:

How to 🎩

🖥 Local development instructions
🗒 General tophatting guidelines
📄 Changelog guidelines

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

import React, {useState, useCallback} from 'react';
import {
  HomeMajorMonotone,
  ProductsMajorTwotone,
  OrdersMajorTwotone,
  OnlineStoreMajorTwotone,
  CirclePlusOutlineMinor,
} from '@shopify/polaris-icons';
import {
  Page,
  Breadcrumbs,
  ResourceItem,
  TextStyle,
  Avatar,
  Card,
  ResourceList,
  Indicator,
  Navigation,
} from '../src';

export function Playground() {
  return (
    <Page title="Playground">
      <Navigation location="/">
        <Navigation.Section
          items={[
            {
              label: 'Home',
              icon: HomeMajorMonotone,
              subNavigationItems: [
                {
                  label: 'sub label',
                  url: '/other',
                  new: true,
                },
              ],
            },
            {
              url: '/path/to/place',
              label: 'Orders',
              icon: OrdersMajorTwotone,
            },
            {
              url: '/path/to/place',
              label: 'Products',
              icon: ProductsMajorTwotone,
            },
          ]}
        />
        <Navigation.Section
          title="Sales channels"
          items={[
            {
              url: '/path/to/place',
              label: 'Online Store',
              icon: OnlineStoreMajorTwotone,
            },
          ]}
          action={{
            accessibilityLabel: 'Add sales channel',
            icon: CirclePlusOutlineMinor,
            onClick: () => {},
          }}
        />
      </Navigation>
    </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]

💦 Potential splash zone of changes introduced to src/**/*.tsx in this pull request:

Files modified	1
Files potentially affected	4

Details

All files potentially affected (total: 4)

• /src/components/Indicator/Indicator.tsx
• /src/components/Navigation/components/Item/Item.tsx
• /src/components/Navigation/components/Section/Section.tsx
• /src/components/Navigation/Navigation.tsx

🎨 src/components/Indicator/Indicator.scss (total: 4)

Files potentially affected (total: 4)

• /src/components/Indicator/Indicator.tsx
• /src/components/Navigation/components/Item/Item.tsx
• /src/components/Navigation/components/Section/Section.tsx
• /src/components/Navigation/Navigation.tsx

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Feedback, troubleshooting: open an issue or reach out on Slack in #polaris-tooling.