Fix invisible Android activity indicator (#33337)

Apply a patch for the React Native `ActivityIndicator` rendering
invisible on Android. This applies the same patch that was previously
applied to the Embed block to to React Native itself.

The core issue in React Native appears to be [wider reaching](https://git.io/JcNlc), but I chose
to [limit the scope](https://git.io/JcNla) of the patch to the one issue we are currently
facing (i.e. invisible activity indicators), as I was concerned applying
a deeper, untested change introducing regressions elsewhere.

packages/block-library/src/embed/embed-loading.native.js

@@ -1,7 +1,7 @@
 /**
  * External dependencies
  */
-import { ActivityIndicator, View, Platform, PlatformColor } from 'react-native';
+import { ActivityIndicator, View } from 'react-native';
 
 /**
  * WordPress dependencies
@@ -19,16 +19,9 @@ const EmbedLoading = () => {
 		styles[ 'embed-preview__loading--dark' ]
 	);
 
-	const activityIndicatorColor = Platform.select( {
-		ios: '#999999', // default color on iOS
-		// ActivityIndicator is blank and does not show up unless explicit color prop is provided.
-		// See https://github.com/facebook/react-native/pull/30057
-		android: PlatformColor( '?attr/colorControlActivated' ),
-	} );
-
 	return (
 		<View style={ style }>
-			<ActivityIndicator animating color={ activityIndicatorColor } />
+			<ActivityIndicator animating />
 		</View>
 	);
 };

patches/react-native+0.64.0.patch

@@ -0,0 +1,25 @@
+diff --git a/node_modules/react-native/Libraries/Components/ActivityIndicator/ActivityIndicator.js b/node_modules/react-native/Libraries/Components/ActivityIndicator/ActivityIndicator.js
+index 52cbda4..3e3b71e 100644
+--- a/node_modules/react-native/Libraries/Components/ActivityIndicator/ActivityIndicator.js
++++ b/node_modules/react-native/Libraries/Components/ActivityIndicator/ActivityIndicator.js
+@@ -14,6 +14,7 @@
+ const Platform = require('../../Utilities/Platform');
+ const React = require('react');
+ const StyleSheet = require('../../StyleSheet/StyleSheet');
++const {PlatformColor} = require('../../StyleSheet/PlatformColorValueTypes');
+ const View = require('../View/View');
+ import type {HostComponent} from '../../Renderer/shims/ReactNativeTypes';
+ import type {ViewProps} from '../View/ViewPropTypes';
+@@ -183,7 +184,11 @@ ActivityIndicatorWithRef.displayName = 'ActivityIndicator';
+  * and run Flow. */
+ ActivityIndicatorWithRef.defaultProps = {
+   animating: true,
+-  color: Platform.OS === 'ios' ? GRAY : null,
++	color: Platform.select({
++     ios: GRAY,
++     android: PlatformColor('?attr/colorControlActivated'),
++     default: null,
++   }),
+   hidesWhenStopped: true,
+   size: 'small',
+ };