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

Libraries/BatchedBridge/__mocks__/MessageQueueTestModule.js

@@ -15,8 +15,8 @@
  * cases.
  */
 const MessageQueueTestModule = {
-  testHook1: function() {},
-  testHook2: function() {},
+  testHook1: function () {},
+  testHook2: function () {},
 };
 
 module.exports = MessageQueueTestModule;