Fix linting issues (#22062)

Summary:
Fixes lots of ESLint warnings. Many of them where in PR #20877 by janicduplessis which requested to split the linting fixes from configuration and package changes.

I solved only the issues that I was most certain about but I would love to get hands on all of them with a little bit of input.
Pull Request resolved: facebook/react-native#22062

Differential Revision: D12889447

Pulled By: TheSavior

fbshipit-source-id: 35f7a08104a5b859c860afdde4af2b32c0685c50

RNTesterUnitTests/RNTesterUnitTestsBundle.js

@@ -9,8 +9,8 @@
 
 'use strict';
 
+// eslint-disable-next-line no-unused-vars
 const __fbBatchedBridge = {
-  // eslint-disable-line no-unused-vars
   flushedQueue: function() {
     return null;
   },

e2e/sanity.test.js

@@ -10,7 +10,7 @@
 describe('Sanity', () => {
   beforeEach(async () => {
     await device.reloadReactNative();
-    await element(by.label(`<Button> Simple React Native button component.`)).tap();
+    await element(by.label('<Button> Simple React Native button component.')).tap();
   });
 
   afterEach(async () => {
@@ -30,7 +30,7 @@ describe('Sanity', () => {
     await element(by.text('OK')).tap();
   });
 
-  it(`Two buttons with JustifyContent:'space-between' should be tappable`, async () => {
+  it("Two buttons with JustifyContent:'space-between' should be tappable", async () => {
     await element(by.label('This looks great!')).tap();
     await expect(element(by.text('Left has been pressed!'))).toBeVisible();
     await element(by.text('OK')).tap();

js/ARTExample.js

@@ -14,7 +14,7 @@ const React = require('react');
 const ReactNative = require('react-native');
 const {ART, Platform, View} = ReactNative;
 
-const {Surface, Path, Group, Transform, Shape} = ART;
+const {Surface, Path, Group, Shape} = ART;
 
 const scale = Platform.isTV ? 4 : 1;
 

js/AsyncStorageExample.js

@@ -55,11 +55,11 @@ class BasicStorageExample extends React.Component<{}, $FlowFixMeState> {
           {'Selected: '}
           <Text style={{color}}>{this.state.selectedValue}</Text>
         </Text>
-        <Text> </Text>
+        <Text />
         <Text onPress={this._removeStorage}>
           Press here to remove from storage.
         </Text>
-        <Text> </Text>
+        <Text />
         <Text>Messages:</Text>
         {this.state.messages.map(m => <Text key={m}>{m}</Text>)}
       </View>

js/XHRExampleFormData.js

@@ -13,11 +13,9 @@
 const React = require('react');
 const ReactNative = require('react-native');
 const {
-  Alert,
   CameraRoll,
   Image,
   ImageEditor,
-  Linking,
   Platform,
   StyleSheet,
   Text,