Add reverseOrder prop to AlphaStack for `flex-direction: column-rev…

…erse` (#7842)

<!--
  ☝️How to write a good PR title:
- Prefix it with [ComponentName] (if applicable), for example: [Button]
  - Start with a verb, for example: Add, Delete, Improve, Fix…
  - Give as much context as necessary and as little as possible
  - Prefix it with [WIP] while it’s a work in progress
-->

### WHY are these changes introduced?

We need `flex-direction: column-reverse` in order to rebuild
`EmptyState`. Adding this to `AlphaStack`

Supports #7809

<!--
  Context about the problem that’s being addressed.
-->

### WHAT is this pull request doing?

<!--
  Summary of the changes committed.

Before / after screenshots are appreciated for UI changes. Make sure to
include alt text that describes the screenshot.

If you include an animated gif showing your change, wrapping it in a
details tag is recommended. Gifs usually autoplay, which can cause
accessibility issues for people reviewing your PR:

    <details>
      <summary>Summary of your gif(s)</summary>
      <img src="..." alt="Description of what the gif shows">
    </details>
-->

<!-- ℹ️ Delete the following for small / trivial changes -->

### How to 🎩

🖥 [Local development
instructions](https://github.com/Shopify/polaris/blob/main/README.md#local-development)
🗒 [General tophatting
guidelines](https://github.com/Shopify/polaris/blob/main/documentation/Tophatting.md)
📄 [Changelog
guidelines](https://github.com/Shopify/polaris/blob/main/.github/CONTRIBUTING.md#changelog)

<!--
  Give as much information as needed to experiment with the component
  in the playground.
-->

<details>
<summary>Copy-paste this code in
<code>playground/Playground.tsx</code>:</summary>

```jsx
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>
  );
}
```

</details>

### 🎩 checklist

- [ ] Tested on
[mobile](https://github.com/Shopify/polaris/blob/main/documentation/Tophatting.md#cross-browser-testing)
- [ ] Tested on [multiple
browsers](https://help.shopify.com/en/manual/shopify-admin/supported-browsers)
- [ ] Tested for
[accessibility](https://github.com/Shopify/polaris/blob/main/documentation/Accessibility%20testing.md)
- [ ] Updated the component's `README.md` with documentation changes
- [ ] [Tophatted
documentation](https://github.com/Shopify/polaris/blob/main/documentation/Tophatting%20documentation.md)
changes in the style guide

.changeset/grumpy-bats-live.md

@@ -0,0 +1,5 @@
+---
+'@shopify/polaris': minor
+---
+
+Add flex-direction: column-reverse to AlphaStack

polaris-react/src/components/AlphaStack/AlphaStack.scss

@@ -13,7 +13,8 @@
   --pc-stack-gap-xl: var(--pc-stack-gap-lg);
   // stylelint-disable-next-line -- generated by polaris-migrator DO NOT COPY
   display: flex;
-  flex-direction: column;
+  // stylelint-disable-next-line -- local component custom property is required for flex direction
+  flex-direction: var(--pc-stack-order);
   // stylelint-disable-next-line -- generated by polaris-migrator DO NOT COPY
   align-items: var(--pc-stack-align);
   // stylelint-disable-next-line -- generated by polaris-migrator DO NOT COPY
@@ -38,10 +39,6 @@
     // stylelint-disable-next-line -- generated by polaris-migrator DO NOT COPY
     gap: var(--pc-stack-gap-xl);
   }
-
-  > * {
-    max-width: 100%;
-  }
 }
 
 .listReset {

polaris-react/src/components/AlphaStack/AlphaStack.tsx

@@ -36,6 +36,8 @@ export interface AlphaStackProps extends React.AriaAttributes {
   gap?: Gap;
   /** HTML id attribute */
   id?: string;
+  /** Toggle order of child items */
+  reverseOrder?: boolean;
 }
 
 export const AlphaStack = ({
@@ -45,6 +47,7 @@ export const AlphaStack = ({
   fullWidth = false,
   gap = '4',
   id,
+  reverseOrder = false,
   ...restProps
 }: AlphaStackProps) => {
   const className = classNames(
@@ -55,6 +58,7 @@ export const AlphaStack = ({
 
   const style = {
     '--pc-stack-align': align ? `${align}` : '',
+    '--pc-stack-order': reverseOrder ? 'column-reverse' : 'column',
     ...getResponsiveProps('stack', 'gap', 'space', gap),
   } as React.CSSProperties;