Minor: Rename AccessibilityInfo.sendAccessibilityEvent_unstable to sendAccessibilityEvent

Summary:
Changelog:
[Internal] Rename AccessibilityInfo.sendAccessibilityEvent_unstable to sendAccessibilityEvent

In Fabric, we want people to use `AccessibilityInfo.sendAccessibilityEvent` instead of `UIManager.sendAccessibilityEvent` for Android. The API is not unstable. There is a test in [AccessibilityExample.js](https://github.com/facebook/react-native/blob/c940eb0c49518b82a3999dcac3027aa70018c763/packages/rn-tester/js/examples/Accessibility/AccessibilityExample.js#L959) in RNTester to confirm that it works.

A search for [`AccessibilityInfo.sendAccessibilityEvent_unstable` in Github](https://github.com/search?q=AccessibilityInfo.sendAccessibilityEvent_unstable&type=Code) shows that it's not being used yet, which makes sense because it's an Fabric API. Therefore it's safe to rename it.

Reviewed By: sammy-SC

Differential Revision: D37901006

fbshipit-source-id: 73f35b09ca8f9337f4d66a431f0a3f815da38249

Author: p-sun

Libraries/Components/AccessibilityInfo/AccessibilityInfo.js

@@ -345,7 +345,7 @@ const AccessibilityInfo: AccessibilityInfoType = {
   /**
    * Send a named accessibility event to a HostComponent.
    */
-  sendAccessibilityEvent_unstable(
+  sendAccessibilityEvent(
     handle: ElementRef<HostComponent<mixed>>,
     eventType: AccessibilityEventTypes,
   ) {

Libraries/ReactNative/BridgelessUIManager.js

@@ -146,7 +146,7 @@ module.exports = {
       errorMessageForMethod('setLayoutAnimationEnabledExperimental'),
     );
   },
-  // Please use AccessibilityInfo.sendAccessibilityEvent_unstable instead.
+  // Please use AccessibilityInfo.sendAccessibilityEvent instead.
   // See SetAccessibilityFocusExample in AccessibilityExample.js for a migration example.
   sendAccessibilityEvent: (reactTag: ?number, eventType: number): void =>
     console.error(errorMessageForMethod('sendAccessibilityEvent')),

jest/setup.js

@@ -133,7 +133,7 @@ jest
       isScreenReaderEnabled: jest.fn(() => Promise.resolve(false)),
       removeEventListener: jest.fn(),
       setAccessibilityFocus: jest.fn(),
-      sendAccessibilityEvent_unstable: jest.fn(),
+      sendAccessibilityEvent: jest.fn(),
       getRecommendedTimeoutMillis: jest.fn(),
     },
   }))

packages/rn-tester/js/examples/Accessibility/AccessibilityExample.js

@@ -956,7 +956,7 @@ function SetAccessibilityFocusExample(props: {}): React.Node {
 
   const onPress = () => {
     if (myRef && myRef.current) {
-      AccessibilityInfo.sendAccessibilityEvent_unstable(myRef.current, 'focus');
+      AccessibilityInfo.sendAccessibilityEvent(myRef.current, 'focus');
     }
   };