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: https://github.com/facebook/react-native/pull/22062

Differential Revision: D12889447

Pulled By: TheSavior

fbshipit-source-id: 35f7a08104a5b859c860afdde4af2b32c0685c50

ReactAndroid/src/androidTest/js/TestIdTestModule.js

@@ -12,7 +12,6 @@
 var Image = require('Image');
 var React = require('React');
 var StyleSheet = require('StyleSheet');
-var Switch = require('Switch');
 var Text = require('Text');
 var TextInput = require('TextInput');
 var TouchableBounce = require('TouchableBounce');