Add reverseOrder prop to AlphaStack for flex-direction: column-reverse (#7842)

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### WHY are these changes introduced?

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

Supports #7809

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### WHAT is this pull request doing?

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

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  return (
    <Page title="Playground">
      {/* Add the code you want to test in here */}
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### 🎩 checklist

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changes in the style guide

Author: Yuraima Estevez

.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;