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/ui/components/elements-inspector/sidebar.tsx

@@ -123,7 +123,7 @@ export class InspectorSidebar extends Component<Props, State> {
 
     const sections: Array<any> =
       (extensions &&
-        extensions.map(ext =>
+        extensions.map((ext) =>
           ext(
             this.props.client,
             this.props.realClient,