Fix <KeyboardAvoidingView> with floating keyboard on iPad (#44859)

Summary:
On iPadOS, users can change the kind of keyboard displayed onscreen, going from normal keyboard, to split keyboard (one half on the left of the screen, one half on the right), or a floating keyboard that you can move around the screen.

When a non-normal kind of keyboard is used, `<KeyboardAvoidingView>` calculations are all wrong and, depending on the `behavior` prop, can make your screen completely hidden.

This PR attempts to detect that the keyboard is not the "normal displayed-at-bottom-of-screen" keyboard, and forces `enable={false}` if this happens.

The approach of comparing the keyboard width with the window width comes from this comment: https://github.com/facebook/react-native/issues/29473#issuecomment-696658937

A better fix might be to detect the kind of keyboard used, but this involves native code changes and I do not know iOS enough to do that. In addition, I have not found an easy way to do it using iOS APIs after a quick search.

I also chose to cache the window width as a class attribute. Maybe this is not needed as `Dimensions.get('window').width` is very fast and can be called on every keyboard event?

This fixes https://github.com/facebook/react-native/issues/44068 and https://github.com/facebook/react-native/issues/29473

[IOS] [FIXED] - Fix `<KeyboardAvoidingView>` with floating keyboard on iPadOS

Pull Request resolved: https://github.com/facebook/react-native/pull/44859

Test Plan:
Tested using RNTester and the "Keyboard Avoiding View with different behaviors" example.

Before:

https://github.com/facebook/react-native/assets/42070/111598a3-286c-464d-8db8-73afb35cd7f9

After:

https://github.com/facebook/react-native/assets/42070/0b3bc94f-8b67-4f42-8a83-e11555080268

Reviewed By: cortinico

Differential Revision: D62844854

Pulled By: cipolleschi

fbshipit-source-id: 577444be50019572955a013969d78178914b5b8d

packages/react-native/Libraries/Components/Keyboard/KeyboardAvoidingView.js

@@ -9,6 +9,7 @@
  */
 
 import type {ViewStyleProp} from '../../StyleSheet/StyleSheet';
+import type {DimensionsPayload} from '../../Utilities/NativeDeviceInfo';
 import type {
   ViewLayout,
   ViewLayoutEvent,
@@ -18,6 +19,7 @@ import type {KeyboardEvent, KeyboardMetrics} from './Keyboard';
 
 import LayoutAnimation from '../../LayoutAnimation/LayoutAnimation';
 import StyleSheet from '../../StyleSheet/StyleSheet';
+import Dimensions from '../../Utilities/Dimensions';
 import Platform from '../../Utilities/Platform';
 import {type EventSubscription} from '../../vendor/emitter/EventEmitter';
 import AccessibilityInfo from '../AccessibilityInfo/AccessibilityInfo';
@@ -66,6 +68,7 @@ class KeyboardAvoidingView extends React.Component<Props, State> {
   viewRef: {current: React.ElementRef<typeof View> | null, ...};
   _initialFrameHeight: number = 0;
   _bottom: number = 0;
+  _windowWidth: number = Dimensions.get('window').width;
 
   constructor(props: Props) {
     super(props);
@@ -130,6 +133,10 @@ class KeyboardAvoidingView extends React.Component<Props, State> {
     }
   };
 
+  _onDimensionsChange = ({window}: DimensionsPayload) => {
+    this._windowWidth = window?.width ?? 0;
+  };
+
   // Avoid unnecessary renders if the KeyboardAvoidingView is disabled.
   _setBottom = (value: number) => {
     const enabled = this.props.enabled ?? true;
@@ -145,6 +152,15 @@ class KeyboardAvoidingView extends React.Component<Props, State> {
       return;
     }
 
+    if (
+      Platform.OS === 'ios' &&
+      this._windowWidth !== this._keyboardEvent.endCoordinates.width
+    ) {
+      // The keyboard is not the standard bottom-of-the-screen keyboard. For example, floating keyboard on iPadOS.
+      this._setBottom(0);
+      return;
+    }
+
     const {duration, easing, endCoordinates} = this._keyboardEvent;
     const height = await this._relativeKeyboardHeight(endCoordinates);
 
@@ -178,6 +194,7 @@ class KeyboardAvoidingView extends React.Component<Props, State> {
     if (Platform.OS === 'ios') {
       this._subscriptions = [
         Keyboard.addListener('keyboardWillChangeFrame', this._onKeyboardChange),
+        Dimensions.addEventListener('change', this._onDimensionsChange),
       ];
     } else {
       this._subscriptions = [