Explicitly type UIManagerProperties (facebook#48587)

Summary:
Pull Request resolved: facebook#48587

Changelog: [Internal]

Reviewed By: cortinico, huntie

Differential Revision: D67977469

fbshipit-source-id: 0f866aeaa3d19ba2bc01d2e4685487c9b1a3329f

Author: j-piasecki

packages/react-native/Libraries/ReactNative/UIManagerProperties.js

@@ -26,7 +26,7 @@
  * accessed. Once UIManager property accesses for view managers has been fully
  * deprecated, this file will also be removed.
  */
-module.exports = [
+const UIManagerProperties: $ReadOnlyArray<string> = [
   'clearJSResponder',
   'configureNextLayoutAnimation',
   'createView',
@@ -59,3 +59,5 @@ module.exports = [
   'genericDirectEventTypes',
   'lazilyLoadView',
 ];
+
+module.exports = UIManagerProperties;

packages/react-native/Libraries/__tests__/__snapshots__/public-api-test.js.snap

@@ -7717,7 +7717,8 @@ declare module.exports: UIManager;
 `;
 
 exports[`public API should not change unintentionally Libraries/ReactNative/UIManagerProperties.js 1`] = `
-"declare module.exports: $FlowFixMe;
+"declare const UIManagerProperties: $ReadOnlyArray<string>;
+declare module.exports: UIManagerProperties;
 "
 `;