[Page] Allow for non-primary page action

[dleroux]

WHY are these changes introduced?

We are bringing back the ability to have a non-primary/indigo button as the pages primary actions. We previously made the decision to remove this ability but there are use cases that having a non-indigo button does make sense.

WHAT is this pull request doing?

Making the default button indigo/primary but allowing the ability to make it a regular button.

How to 🎩

🖥 Local development instructions
🗒 General tophatting guidelines
📄 Changelog guidelines

Paste the code below in the playground and toggle primary key of the primaryAction.

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

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

export function Playground() {
  return (
    <Page
      breadcrumbs={[{content: 'Products'}]}
      title="Product reviews"
      primaryAction={{
        content: 'Save',
        disabled: true,
        primary: false,
      }}
      secondaryActions={[{content: 'Duplicate'}, {content: 'Upgrade'}]}
      actionGroups={[
        {
          title: 'Promote',
          actions: [
            {
              content: 'Share on Facebook',
            },
            {
              content: 'Share on Pinterest',
            },
          ],
        },
      ]}
    >
      <p>Page content</p>
    </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

[AndrewMusgrave]

Would we want a primary action to be non-primary?

[sarahill]

For additional context on this:

This was brought from @simon-callsen in the #polaris slack channel. A change had been made the page component that only allowed primary-buttons in the page header. This generally makes sense for the way the component was originally designed, but teams now have a need to use this in different ways that break that pattern.

The team discussed this in Slack and came to the conclusion that it's worth reverting that change and allowing non-primary actions in the page header.

There's a big opportunity here to revisit the component and consider how we can make this flexible for teams and their different use cases.

PR that introduced the change to allow only primary actions #1653

[sarahill]

This lgtm! Thanks for doing this, Dan ✨