Upgrade Prettier from 1.17 to 2.0.2.

Summary:
This gets us on the latest Prettier 2.x:
https://prettier.io/blog/2020/03/21/2.0.0.html

Notably, this adds support for TypeScript 3.8,
which introduces new syntax, such as `import type`.

Reviewed By: zertosh

Differential Revision: D20636268

fbshipit-source-id: fca5833d003804333a05ba16325bbbe0e06d6c8a

ReactAndroid/src/androidTest/js/ImageErrorTestApp.js

@@ -15,7 +15,7 @@ const {Image, NativeModules, StyleSheet, View} = require('react-native');
 const {Recording: RecordingModule} = NativeModules;
 
 class ImageErrorTestApp extends React.Component {
-  onError = e => {
+  onError = (e) => {
     RecordingModule.record('Got error: ' + e.nativeEvent.error);
   };