fix(View): map aria-modal to accessibilityViewIsModal (#59328)

Summary:
The `View` docs list `aria-modal` as an iOS prop that "has precedence over the
`accessibilityViewIsModal` prop". `View` does not map it, though: `View.js`
converts `aria-label`, `aria-live`, `aria-hidden` and the other `aria-*` props
to their `accessibility*` forms, but `aria-modal` is passed through unchanged,
and the native side only reads `accessibilityViewIsModal`. As a result
`<View aria-modal>` does nothing, and VoiceOver can still reach the views
behind a custom dialog.

When `aria-modal` was added in #34506, it was mapped in `Pressable` and the
`Touchable*` components and added to `ViewPropTypes`, but `View.js` itself was
not changed, so the prop is typed and documented on `View` but has no effect
there.

This change maps `aria-modal` to `accessibilityViewIsModal` in `View`, with
`aria-modal` taking precedence, as documented.

## Changelog:

[IOS] [FIXED] - `aria-modal` on `View` now sets `accessibilityViewIsModal`

Pull Request resolved: #59328

Test Plan:
Checked on an iPhone (iOS 27) with React Native 0.88.0 (Expo SDK 58,
development build), VoiceOver on. A screen with three background buttons and a
custom overlay that is their sibling:

```tsx
import { useState } from 'react';
import { Pressable, Text, View } from 'react-native';

export default function App() {
  const [open, setOpen] = useState(false);
  return (
    <View style={{ flex: 1 }}>
      <View style={{ flex: 1, padding: 48, gap: 16 }}>
        {['One', 'Two', 'Three'].map((title) => (
          <Pressable key={title} role="button">
            <Text>Background item {title}</Text>
          </Pressable>
        ))}
        <Pressable role="button" onPress={() => setOpen(true)}>
          <Text>Open the dialog</Text>
        </Pressable>
      </View>
      {open && (
        <View
          aria-modal
          style={{
            position: 'absolute',
            inset: 0,
            justifyContent: 'center',
            padding: 32,
            backgroundColor: 'rgba(0,0,0,0.4)',
          }}
        >
          <View style={{ backgroundColor: 'white', padding: 24, gap: 16 }}>
            <Text role="heading">Dialog</Text>
            <Pressable role="button" onPress={() => setOpen(false)}>
              <Text>Close</Text>
            </Pressable>
          </View>
        </View>
      )}
    </View>
  );
}
```

Before: with the dialog open, swiping right goes past "Close" to the
"Background item" buttons, and touching where they are focuses them.
Replacing `aria-modal` with `accessibilityViewIsModal` keeps focus inside the
dialog.

After: `aria-modal` behaves the same as `accessibilityViewIsModal`.

Reviewed By: andrewdacenko

Differential Revision: D126904378

Pulled By: javache

fbshipit-source-id: 698cceaa5ad45c68c6fd9eb7fa002da4901a7aa1

Author: faciledictu

packages/react-native/Libraries/Components/View/View.js

@@ -50,6 +50,7 @@ component View(ref?: React.RefSetter<ViewInstance>, ...props: ViewProps) {
     'aria-label': ariaLabel,
     'aria-labelledby': ariaLabelledBy,
     'aria-live': ariaLive,
+    'aria-modal': ariaModal,
     'aria-selected': ariaSelected,
     'aria-valuemax': ariaValueMax,
     'aria-valuemin': ariaValueMin,
@@ -76,6 +77,10 @@ component View(ref?: React.RefSetter<ViewInstance>, ...props: ViewProps) {
       ariaLive === 'off' ? 'none' : ariaLive;
   }
 
+  if (ariaModal !== undefined) {
+    resolvedProps.accessibilityViewIsModal = ariaModal;
+  }
+
   if (ariaHidden !== undefined) {
     resolvedProps.accessibilityElementsHidden = ariaHidden;
     if (ariaHidden === true) {