prettier 2

Summary:
Quick notes:

- This looks worse than it is. It adds mandatory parentheses to single argument lambdas. Lots of outrage on Twitter about it, personally I'm {emoji:1f937_200d_2642} about it.
- Space before function, e.g. `a = function ()` is now enforced. I like this because both were fine before.
- I added `eslint-config-prettier` to the config because otherwise a ton of rules conflict with eslint itself.

Close https://github.com/facebook/flipper/pull/915

Reviewed By: jknoxville

Differential Revision: D20594929

fbshipit-source-id: ca1c65376b90e009550dd6d1f4e0831d32cbff03

desktop/app/src/utils/__tests__/Idler.node.js

@@ -64,7 +64,7 @@ test('TestIdler can be controlled', async () => {
   expect(idler.shouldIdle()).toBe(true);
 
   let threw = false;
-  const p = idler.idle().catch(e => {
+  const p = idler.idle().catch((e) => {
     threw = true;
     expect(e).toMatchInlineSnapshot(
       `[CancelledPromiseError: Idler got killed]`,

desktop/app/src/utils/__tests__/jsonFileStorage.node.js

@@ -26,7 +26,7 @@ const storage = new JsonFileStorage(
 test('A valid settings file gets parsed correctly', () => {
   return storage
     .getItem('anykey')
-    .then(result => expect(result).toEqual(validDeserializedData));
+    .then((result) => expect(result).toEqual(validDeserializedData));
 });
 
 test('deserialize works as expected', () => {