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/Idler.tsx

@@ -34,7 +34,7 @@ export class Idler implements BaseIdler {
     const now = performance.now();
     if (now - this.lastIdle > this.interval) {
       this.lastIdle = now;
-      return new Promise(resolve => {
+      return new Promise((resolve) => {
         if (typeof requestIdleCallback !== 'undefined') {
           requestIdleCallback(() => {
             resolve();
@@ -88,7 +88,7 @@ export class TestIdler implements BaseIdler {
     if (this.resolver) {
       throw new Error('Already idling');
     }
-    return new Promise<void>(resolve => {
+    return new Promise<void>((resolve) => {
       this.resolver = () => {
         this.resolver = undefined;
         this.hasProgressed = false;