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

RNTester/js/examples/TurboModule/SampleTurboModuleExample.js

@@ -40,17 +40,17 @@ class SampleTurboModuleExample extends React.Component<{||}, State> {
   // Add calls to methods in TurboModule here
   _tests = {
     callback: () =>
-      NativeSampleTurboModule.getValueWithCallback(callbackValue =>
+      NativeSampleTurboModule.getValueWithCallback((callbackValue) =>
         this._setResult('callback', callbackValue),
       ),
     promise: () =>
-      NativeSampleTurboModule.getValueWithPromise(false).then(valuePromise =>
+      NativeSampleTurboModule.getValueWithPromise(false).then((valuePromise) =>
         this._setResult('promise', valuePromise),
       ),
     rejectPromise: () =>
       NativeSampleTurboModule.getValueWithPromise(true)
         .then(() => {})
-        .catch(e => this._setResult('rejectPromise', e.message)),
+        .catch((e) => this._setResult('rejectPromise', e.message)),
     getConstants: () => NativeSampleTurboModule.getConstants(),
     voidFunc: () => NativeSampleTurboModule.voidFunc(),
     getBool: () => NativeSampleTurboModule.getBool(true),
@@ -101,7 +101,7 @@ class SampleTurboModuleExample extends React.Component<{||}, State> {
     }
     if (Platform.OS === 'ios') {
       // iOS is fully implemented, so show all results immediately.
-      Object.keys(this._tests).forEach(item =>
+      Object.keys(this._tests).forEach((item) =>
         this._setResult(item, this._tests[item]()),
       );
     }
@@ -114,7 +114,7 @@ class SampleTurboModuleExample extends React.Component<{||}, State> {
           <TouchableOpacity
             style={[styles.column, styles.button]}
             onPress={() =>
-              Object.keys(this._tests).forEach(item =>
+              Object.keys(this._tests).forEach((item) =>
                 this._setResult(item, this._tests[item]()),
               )
             }>
@@ -128,12 +128,12 @@ class SampleTurboModuleExample extends React.Component<{||}, State> {
         </View>
         <FlatList
           data={Object.keys(this._tests)}
-          keyExtractor={item => item}
+          keyExtractor={(item) => item}
           renderItem={({item}) => (
             <View style={styles.item}>
               <TouchableOpacity
                 style={[styles.column, styles.button]}
-                onPress={e => this._setResult(item, this._tests[item]())}>
+                onPress={(e) => this._setResult(item, this._tests[item]())}>
                 <Text style={styles.buttonText}>{item}</Text>
               </TouchableOpacity>
               <View style={[styles.column]}>{this._renderResult(item)}</View>